540 lines
16 KiB
JavaScript
540 lines
16 KiB
JavaScript
/**
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* @fileoverview Rule to preserve caught errors when re-throwing exceptions
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* @author Amnish Singh Arora
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require("./utils/ast-utils");
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//------------------------------------------------------------------------------
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// Types
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//------------------------------------------------------------------------------
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/** @typedef {import("estree").Node} ASTNode */
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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/*
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* This is an indicator of an error cause node, that is too complicated to be detected and fixed.
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* Eg, when error options is an `Identifier` or a `SpreadElement`.
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*/
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const UNKNOWN_CAUSE = Symbol("unknown_cause");
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const BUILT_IN_ERROR_TYPES = new Set([
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"Error",
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"EvalError",
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"RangeError",
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"ReferenceError",
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"SyntaxError",
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"TypeError",
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"URIError",
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"AggregateError",
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]);
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/**
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* Finds and returns information about the `cause` property of an error being thrown.
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* @param {ASTNode} throwStatement `ThrowStatement` to be checked.
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* @returns {{ value: ASTNode; multipleDefinitions: boolean; } | UNKNOWN_CAUSE | null}
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* Information about the `cause` of the error being thrown, such as the value node and
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* whether there are multiple definitions of `cause`. `null` if there is no `cause`.
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*/
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function getErrorCause(throwStatement) {
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const throwExpression = throwStatement.argument;
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/*
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* Determine which argument index holds the options object
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* `AggregateError` is a special case as it accepts the `options` object as third argument.
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*/
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const optionsIndex =
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throwExpression.callee.name === "AggregateError" ? 2 : 1;
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/*
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* Make sure there is no `SpreadElement` at or before the `optionsIndex`
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* as this messes up the effective order of arguments and makes it complicated
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* to track where the actual error options need to be at
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*/
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const spreadExpressionIndex = throwExpression.arguments.findIndex(
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arg => arg.type === "SpreadElement",
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);
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if (spreadExpressionIndex >= 0 && spreadExpressionIndex <= optionsIndex) {
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return UNKNOWN_CAUSE;
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}
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const errorOptions = throwExpression.arguments[optionsIndex];
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if (errorOptions) {
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if (errorOptions.type === "ObjectExpression") {
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if (
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errorOptions.properties.some(
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prop => prop.type === "SpreadElement",
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)
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) {
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/*
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* If there is a spread element as part of error options, it is too complicated
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* to verify if the cause is used properly and auto-fix.
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*/
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return UNKNOWN_CAUSE;
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}
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const causeProperties = errorOptions.properties.filter(
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prop =>
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prop.type === "Property" &&
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prop.key.type === "Identifier" &&
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prop.key.name === "cause" &&
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!prop.computed, // It is hard to accurately identify the value of computed props
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);
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const causeProperty = causeProperties.at(-1);
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return causeProperty
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? {
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value: causeProperty.value,
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multipleDefinitions: causeProperties.length > 1,
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}
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: null;
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}
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// Error options exist, but too complicated to be analyzed/fixed
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return UNKNOWN_CAUSE;
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}
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return null;
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}
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/**
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* Finds and returns the `CatchClause` node, that the `node` is part of.
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* @param {ASTNode} node The AST node to be evaluated.
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* @returns {ASTNode | null } The closest parent `CatchClause` node, `null` if the `node` is not in a catch block.
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*/
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function findParentCatch(node) {
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let currentNode = node;
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while (currentNode && currentNode.type !== "CatchClause") {
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if (
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[
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"FunctionDeclaration",
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"FunctionExpression",
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"ArrowFunctionExpression",
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"StaticBlock",
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].includes(currentNode.type)
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) {
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/*
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* Make sure the ThrowStatement is not made inside a function definition or a static block inside a high level catch.
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* In such cases, the caught error is not directly related to the Throw.
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*
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* For example,
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* try {
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* } catch (error) {
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* foo = {
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* bar() {
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* throw new Error();
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* }
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* };
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* }
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*/
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return null;
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}
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currentNode = currentNode.parent;
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}
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return currentNode;
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}
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../types').Rule.RuleModule} */
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module.exports = {
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meta: {
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type: "suggestion",
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defaultOptions: [
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{
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requireCatchParameter: false,
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},
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],
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docs: {
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description:
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"Disallow losing originally caught error when re-throwing custom errors",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/preserve-caught-error", // URL to the documentation page for this rule
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},
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/*
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* TODO: We should allow passing `customErrorTypes` option once something like `typescript-eslint`'s
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* `TypeOrValueSpecifier` is implemented in core Eslint.
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* See:
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* 1. https://typescript-eslint.io/packages/type-utils/type-or-value-specifier/
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* 2. https://github.com/eslint/eslint/pull/19913#discussion_r2192608593
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* 3. https://github.com/eslint/eslint/discussions/16540
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*/
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schema: [
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{
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type: "object",
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properties: {
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requireCatchParameter: {
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type: "boolean",
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description:
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"Requires the catch blocks to always have the caught error parameter so it is not discarded.",
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},
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},
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additionalProperties: false,
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},
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],
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messages: {
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missingCause:
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"There is no `cause` attached to the symptom error being thrown.",
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incorrectCause:
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"The symptom error is being thrown with an incorrect `cause`.",
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includeCause:
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"Include the original caught error as the `cause` of the symptom error.",
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missingCatchErrorParam:
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"The caught error is not accessible because the catch clause lacks the error parameter. Start referencing the caught error using the catch parameter.",
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partiallyLostError:
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"Re-throws cannot preserve the caught error as a part of it is being lost due to destructuring.",
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caughtErrorShadowed:
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"The caught error is being attached as `cause`, but is shadowed by a closer scoped redeclaration.",
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},
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hasSuggestions: true,
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},
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create(context) {
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const sourceCode = context.sourceCode;
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const [{ requireCatchParameter }] = context.options;
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//----------------------------------------------------------------------
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// Helpers
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//----------------------------------------------------------------------
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/**
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* Checks if a `ThrowStatement` is constructing and throwing a new `Error` object.
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*
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* Covers all the error types on `globalThis` that support `cause` property:
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* https://github.com/microsoft/TypeScript/blob/main/src/lib/es2022.error.d.ts
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* @param {ASTNode} throwStatement The `ThrowStatement` that needs to be checked.
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* @returns {boolean} `true` if a new "Error" is being thrown, else `false`.
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*/
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function isThrowingNewError(throwStatement) {
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return (
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(throwStatement.argument.type === "NewExpression" ||
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throwStatement.argument.type === "CallExpression") &&
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throwStatement.argument.callee.type === "Identifier" &&
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BUILT_IN_ERROR_TYPES.has(throwStatement.argument.callee.name) &&
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/*
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* Make sure the thrown Error is instance is one of the built-in global error types.
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* Custom imports could shadow this, which would lead to false positives.
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* e.g. import { Error } from "./my-custom-error.js";
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* throw Error("Failed to perform error prone operations");
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*/
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sourceCode.isGlobalReference(throwStatement.argument.callee)
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);
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}
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/**
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* Inserts `cause: <caughtErrorName>` into an inline options object expression.
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* @param {RuleFixer} fixer The fixer object.
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* @param {ASTNode} optionsNode The options object node.
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* @param {string} caughtErrorName The name of the caught error (e.g., "err").
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* @returns {Fix} The fix object.
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*/
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function insertCauseIntoOptions(fixer, optionsNode, caughtErrorName) {
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const properties = optionsNode.properties;
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if (properties.length === 0) {
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// Insert inside empty braces: `{}` → `{ cause: err }`
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return fixer.insertTextAfter(
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sourceCode.getFirstToken(optionsNode),
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`cause: ${caughtErrorName}`,
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);
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}
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const lastProp = properties.at(-1);
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return fixer.insertTextAfter(
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lastProp,
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`, cause: ${caughtErrorName}`,
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);
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}
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//----------------------------------------------------------------------
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// Public
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//----------------------------------------------------------------------
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return {
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ThrowStatement(node) {
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// Check if the throw is inside a catch block
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const parentCatch = findParentCatch(node);
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const throwStatement = node;
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// Check if a new error is being thrown in a catch block
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if (parentCatch && isThrowingNewError(throwStatement)) {
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if (
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parentCatch.param &&
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parentCatch.param.type !== "Identifier"
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) {
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/*
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* When a part of the caught error is being lost at the parameter level, commonly due to destructuring.
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* e.g. catch({ message, ...rest })
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*/
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context.report({
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messageId: "partiallyLostError",
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node: parentCatch,
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});
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return;
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}
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const caughtError =
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parentCatch.param?.type === "Identifier"
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? parentCatch.param
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: null;
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// Check if there are throw statements and caught error is being ignored
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if (!caughtError) {
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if (requireCatchParameter) {
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context.report({
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node: throwStatement,
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messageId: "missingCatchErrorParam",
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});
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return;
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}
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return;
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}
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// Check if there is a cause attached to the new error
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const errorCauseInfo = getErrorCause(throwStatement);
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if (errorCauseInfo === UNKNOWN_CAUSE) {
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// Error options exist, but too complicated to be analyzed/fixed
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return;
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}
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if (errorCauseInfo === null) {
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// If there is no `cause` attached to the error being thrown.
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context.report({
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messageId: "missingCause",
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node: throwStatement,
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suggest: [
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{
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messageId: "includeCause",
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fix(fixer) {
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const throwExpression =
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throwStatement.argument;
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const args = throwExpression.arguments;
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const errorType =
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throwExpression.callee.name;
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// AggregateError: errors, message, options
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if (errorType === "AggregateError") {
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const errorsArg = args[0];
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const messageArg = args[1];
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const optionsArg = args[2];
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if (!errorsArg) {
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// Case: `throw new AggregateError()` → insert all arguments
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const lastToken =
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sourceCode.getLastToken(
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throwExpression,
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);
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const lastCalleeToken =
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sourceCode.getLastToken(
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throwExpression.callee,
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);
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const parenToken =
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sourceCode.getFirstTokenBetween(
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lastCalleeToken,
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lastToken,
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astUtils.isOpeningParenToken,
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);
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if (parenToken) {
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return fixer.insertTextAfter(
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parenToken,
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`[], "", { cause: ${caughtError.name} }`,
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);
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}
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return fixer.insertTextAfter(
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throwExpression.callee,
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`([], "", { cause: ${caughtError.name} })`,
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);
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}
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if (!messageArg) {
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// Case: `throw new AggregateError([])` → insert message and options
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return fixer.insertTextAfter(
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errorsArg,
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`, "", { cause: ${caughtError.name} }`,
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);
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}
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if (!optionsArg) {
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// Case: `throw new AggregateError([], "")` → insert error options only
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return fixer.insertTextAfter(
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messageArg,
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`, { cause: ${caughtError.name} }`,
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);
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}
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if (
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optionsArg.type ===
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"ObjectExpression"
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) {
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return insertCauseIntoOptions(
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fixer,
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optionsArg,
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caughtError.name,
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);
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}
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// Complex dynamic options — skip
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return null;
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}
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// Normal Error types
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const messageArg = args[0];
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const optionsArg = args[1];
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if (!messageArg) {
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// Case: `throw new Error()` → insert both message and options
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const lastToken =
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sourceCode.getLastToken(
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throwExpression,
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);
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const lastCalleeToken =
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sourceCode.getLastToken(
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throwExpression.callee,
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);
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const parenToken =
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sourceCode.getFirstTokenBetween(
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lastCalleeToken,
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lastToken,
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astUtils.isOpeningParenToken,
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);
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if (parenToken) {
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return fixer.insertTextAfter(
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parenToken,
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`"", { cause: ${caughtError.name} }`,
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);
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}
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return fixer.insertTextAfter(
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throwExpression.callee,
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`("", { cause: ${caughtError.name} })`,
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);
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}
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if (!optionsArg) {
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// Case: `throw new Error("Some message")` → insert only options
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return fixer.insertTextAfter(
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messageArg,
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`, { cause: ${caughtError.name} }`,
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);
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}
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if (
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optionsArg.type ===
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"ObjectExpression"
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) {
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return insertCauseIntoOptions(
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fixer,
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optionsArg,
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caughtError.name,
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);
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}
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return null; // Identifier or spread — do not fix
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},
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},
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],
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});
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// We don't need to check further
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return;
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}
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const { value: thrownErrorCause } = errorCauseInfo;
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// If there is an attached cause, verify that it matches the caught error
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if (
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!(
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thrownErrorCause.type === "Identifier" &&
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thrownErrorCause.name === caughtError.name
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)
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) {
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const suggest = errorCauseInfo.multipleDefinitions
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? null // If there are multiple `cause` definitions, a suggestion could be confusing.
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: [
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{
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messageId: "includeCause",
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fix(fixer) {
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/*
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* In case `cause` is attached using object property shorthand or as a method or accessor.
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* e.g. throw Error("fail", { cause });
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* throw Error("fail", { cause() { doSomething(); } });
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* throw Error("fail", { get cause() { return error; } });
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*/
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if (
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thrownErrorCause.parent
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.method ||
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thrownErrorCause.parent
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.shorthand ||
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thrownErrorCause.parent.kind !==
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"init"
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) {
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return fixer.replaceText(
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thrownErrorCause.parent,
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`cause: ${caughtError.name}`,
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);
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}
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return fixer.replaceText(
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thrownErrorCause,
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caughtError.name,
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);
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},
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},
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];
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context.report({
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messageId: "incorrectCause",
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node: thrownErrorCause,
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suggest,
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});
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return;
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}
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/*
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* If the attached cause matches the identifier name of the caught error,
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* make sure it is not being shadowed by a closer scoped redeclaration.
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*
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* e.g. try {
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* doSomething();
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* } catch (error) {
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* if (whatever) {
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* const error = anotherError;
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* throw new Error("Something went wrong");
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* }
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* }
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*/
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let scope = sourceCode.getScope(throwStatement);
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do {
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const variable = scope.set.get(caughtError.name);
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if (variable) {
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break;
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}
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scope = scope.upper;
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} while (scope);
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if (scope?.block !== parentCatch) {
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// Caught error is being shadowed
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context.report({
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messageId: "caughtErrorShadowed",
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node: throwStatement,
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});
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}
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}
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},
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};
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},
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};
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