worker: fix crash when a worker joins after exit

If a worker has not already joined before running to completion
it will join in a SetImmediateThreadsafe which could occur after
the worker has already ended by other means. Mutating a JS object
at that point would fail because the isolate is already disposed.

Author: Qard

src/node_worker.cc

@@ -453,10 +453,12 @@ void Worker::JoinThread() {
     HandleScope handle_scope(env()->isolate());
     Context::Scope context_scope(env()->context());
 
+    // TODO(qard): Do we need to move this, or can we just drop it entirely?
+    // See: https://github.com/nodejs/node/issues/56020
     // Reset the parent port as we're closing it now anyway.
-    object()->Set(env()->context(),
-                  env()->message_port_string(),
-                  Undefined(env()->isolate())).Check();
+    // object()->Set(env()->context(),
+    //               env()->message_port_string(),
+    //               Undefined(env()->isolate())).Check();
 
     Local<Value> args[] = {
         Integer::New(env()->isolate(), static_cast<int>(exit_code_)),