src: allow fatal exceptions to be enhanced

This commit allows fatal exceptions to be enhanced so that
exceptions thrown from an unhandledException handler have
the stack attached properly.

PR-URL: https://github.com/nodejs/node/pull/28562
Fixes: https://github.com/nodejs/node/issues/28550
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

src/node_errors.cc

@@ -448,10 +448,11 @@ TryCatchScope::~TryCatchScope() {
     HandleScope scope(env_->isolate());
     Local<v8::Value> exception = Exception();
     Local<v8::Message> message = Message();
+    EnhanceFatalException enhance = CanContinue() ?
+        EnhanceFatalException::kEnhance : EnhanceFatalException::kDontEnhance;
     if (message.IsEmpty())
       message = Exception::CreateMessage(env_->isolate(), exception);
-    ReportFatalException(
-        env_, exception, message, EnhanceFatalException::kDontEnhance);
+    ReportFatalException(env_, exception, message, enhance);
     env_->Exit(7);
   }
 }

test/parallel/test-unhandled-exception-rethrow-error.js

@@ -0,0 +1,28 @@
+'use strict';
+require('../common');
+
+if (process.argv[2] === 'child') {
+  process.on('uncaughtException', (err) => {
+    err.rethrow = true;
+    throw err;
+  });
+
+  function throwException() {
+    throw new Error('boom');
+  }
+
+  throwException();
+} else {
+  const assert = require('assert');
+  const { spawnSync } = require('child_process');
+  const result = spawnSync(process.execPath, [__filename, 'child']);
+
+  assert.strictEqual(result.status, 7);
+  assert.strictEqual(result.signal, null);
+  assert.strictEqual(result.stdout.toString().trim(), '');
+  // Verify that the error was thrown and that the stack was preserved.
+  const stderr = result.stderr.toString();
+  assert(/Error: boom/.test(stderr));
+  assert(/at throwException/.test(stderr));
+  assert(/rethrow: true/.test(stderr));
+}