fix: unclean crash on provider resolution failure

go.mod

@@ -1,6 +1,6 @@
 module github.com/janishutz/oidclogin
 
-go 1.27.1
+go 1.26.0
 
 require (
 	github.com/coreos/go-oidc/v3 v3.21.0

main.go

@@ -56,12 +56,12 @@ func Configure(r *gin.Engine, app_url string, default_redirect string, stubs_on_
 	}
 
 	provider, err := oidc.NewProvider(context.Background(), issuer)
-	verifier = *provider.Verifier(&oidc.Config{ClientID: clientID})
-
 	if err != nil {
 		log.Fatal("[JHID] Provider resolution failed with error", err)
 	}
 
+	verifier = *provider.Verifier(&oidc.Config{ClientID: clientID})
+
 	config = oauth2.Config{
 		ClientID:     clientID,
 		ClientSecret: clientSecret,