fix: Ensure crash error messages are not duplicated

bin/eslint.js

@@ -92,6 +92,14 @@ function getErrorMessage(error) {
     return util.format("%o", error);
 }
 
+/**
+ * Tracks error messages that are shown to the user so we only ever show the
+ * same message once.
+ * @type {Set<string>}
+ */
+
+const displayedErrors = new Set();
+
 /**
  * Catch and report unexpected error.
  * @param {any} error The thrown error object.
@@ -101,14 +109,17 @@ function onFatalError(error) {
     process.exitCode = 2;
 
     const { version } = require("../package.json");
-    const message = getErrorMessage(error);
-
-    console.error(`
+    const message = `
 Oops! Something went wrong! :(
 
 ESLint: ${version}
 
-${message}`);
+${getErrorMessage(error)}`;
+
+    if (!displayedErrors.has(message)) {
+        console.error(message);
+        displayedErrors.add(message);
+    }
 }
 
 //------------------------------------------------------------------------------

tests/bin/eslint.js

@@ -387,6 +387,36 @@ describe("bin/eslint.js", () => {
             return Promise.all([exitCodeAssertion, outputAssertion]);
         });
 
+        // https://github.com/eslint/eslint/issues/17560
+        describe("does not print duplicate errors in the event of a crash", () => {
+
+            it("when there is an invalid config read from a config file", () => {
+                const config = path.join(__dirname, "../fixtures/bin/eslint.config-invalid.js");
+                const child = runESLint(["--config", config, "conf", "tools"]);
+                const exitCodeAssertion = assertExitCode(child, 2);
+                const outputAssertion = getOutput(child).then(output => {
+
+                    // The error text should appear exactly once in stderr
+                    assert.strictEqual(output.stderr.match(/A config object is using the "globals" key/gu).length, 1);
+                });
+
+                return Promise.all([exitCodeAssertion, outputAssertion]);
+            });
+
+            it("when there is an error in the next tick", () => {
+                const config = path.join(__dirname, "../fixtures/bin/eslint.config-tick-throws.js");
+                const child = runESLint(["--config", config, "Makefile.js"]);
+                const exitCodeAssertion = assertExitCode(child, 2);
+                const outputAssertion = getOutput(child).then(output => {
+
+                    // The error text should appear exactly once in stderr
+                    assert.strictEqual(output.stderr.match(/test_error_stack/gu).length, 1);
+                });
+
+                return Promise.all([exitCodeAssertion, outputAssertion]);
+            });
+        });
+
         it("prints the error message pointing to line of code", () => {
             const invalidConfig = path.join(__dirname, "../fixtures/bin/eslint.config.js");
             const child = runESLint(["--no-ignore", "-c", invalidConfig]);

tests/fixtures/bin/eslint.config-invalid.js

@@ -0,0 +1,3 @@
+module.exports = [{
+    globals: {}
+}];

tests/fixtures/bin/eslint.config-tick-throws.js

@@ -0,0 +1,24 @@
+function throwError() {
+    const error = new Error();
+    error.stack = "test_error_stack";
+    throw error;
+}
+
+module.exports = [{
+    plugins: {
+        foo: {
+            rules: {
+                bar: {
+                    create() {
+                        process.nextTick(throwError);
+                        process.nextTick(throwError);
+                        return {};
+                    }
+                }
+            }
+        }
+    },
+    rules: {
+        "foo/bar": "error"
+    }
+}];