vm: do not overwrite error when creating context

An empty `Local<>` already indicates that an exception is pending,
so there is no need to throw an exception. In the case of Workers,
this could override a `.terminate()` call.

PR-URL: #26112
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: addaleax

src/node_contextify.cc

@@ -171,7 +171,6 @@ MaybeLocal<Context> ContextifyContext::CreateV8Context(
   Local<Context> ctx = NewContext(env->isolate(), object_template);
 
   if (ctx.IsEmpty()) {
-    env->ThrowError("Could not instantiate context");
     return MaybeLocal<Context>();
   }
 

test/parallel/test-worker-vm-context-terminate.js

@@ -0,0 +1,19 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const vm = require('vm');
+const { Worker } = require('worker_threads');
+
+// 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('online', common.mustCall(() => {
+    setTimeout(() => w.terminate(), 50);
+  }));
+  w.on('error', common.mustNotCall());
+  w.on('exit', common.mustCall((code) => assert.strictEqual(code, 1)));
+} else {
+  while (true)
+    vm.runInNewContext('');
+}