worker: fix process._fatalException return type

This makes sure `process._fatalException()` returns a boolean when
run inside of a worker.

PR-URL: https://github.com/nodejs/node/pull/29706
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>

lib/internal/main/worker_thread.js

@@ -166,7 +166,10 @@ function workerOnGlobalUncaughtException(error, fromPromise) {
   }
   debug(`[${threadId}] uncaught exception handled = ${handled}`);
 
-  if (!handled) {
+  if (handled) {
+    return true;
+  }
+
   let serialized;
   try {
     const { serializeError } = require('internal/error-serdes');
@@ -185,7 +188,6 @@ function workerOnGlobalUncaughtException(error, fromPromise) {
   clearAsyncIdStack();
 
   process.exit();
-  }
 }
 
 // Patch the global uncaught exception handler so it gets picked up by

test/parallel/test-worker-non-fatal-uncaught-exception.js

@@ -0,0 +1,25 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { Worker } = require('worker_threads');
+
+// Check that `process._fatalException()` returns a boolean when run inside a
+// worker.
+
+// Do not use isMainThread so that this test itself can be run inside a Worker.
+if (!process.env.HAS_STARTED_WORKER) {
+  process.env.HAS_STARTED_WORKER = 1;
+  const w = new Worker(__filename);
+  w.on('exit', common.mustCall((code) => {
+    assert.strictEqual(code, 0);
+  }));
+  return;
+}
+
+process.once('uncaughtException', () => {
+  process.nextTick(() => {
+    assert.strictEqual(res, true);
+  });
+});
+
+const res = process._fatalException(new Error());