worker: parse NODE_OPTIONS when env option is not provided

src/node_worker.cc

@@ -561,7 +561,7 @@ void Worker::New(const FunctionCallbackInfo<Value>& args) {
     THROW_ERR_OPERATION_FAILED(env, "Failed to copy environment variables");
   }
 
-  if (args[1]->IsObject() || args[2]->IsArray()) {
+  if (args[1]->IsNull() || args[1]->IsObject() || args[2]->IsArray()) {
     per_isolate_opts.reset(new PerIsolateOptions());
 
     HandleEnvOptions(per_isolate_opts->per_env, [&env_vars](const char* name) {

test/fixtures/spawn-worker-without-env-option.js

@@ -0,0 +1,17 @@
+'use strict';
+
+// Tests that NODE_OPTIONS set at runtime in the parent process
+// are picked up by a worker thread even when the env option is
+// not explicitly provided to the Worker constructor.
+const { Worker, isMainThread } = require('worker_threads');
+
+if (isMainThread) {
+  process.env.NODE_OPTIONS = '--trace-exit';
+  new Worker(__filename);
+} else {
+  setImmediate(() => {
+    process.nextTick(() => {
+      process.exit(0);
+    });
+  });
+}

test/parallel/test-worker-node-options.js

@@ -38,3 +38,20 @@ spawnSyncAndAssert(
     stderr: /spawn-worker-with-trace-exit\.js:17/
   }
 );
+
+// Test that NODE_OPTIONS set at runtime in the parent process are
+// picked up by a worker even when the env option is not provided.
+spawnSyncAndAssert(
+  process.execPath,
+  [
+    fixtures.path('spawn-worker-without-env-option'),
+  ],
+  {
+    env: {
+      ...process.env,
+    }
+  },
+  {
+    stderr: /spawn-worker-without-env-option\.js:14/
+  }
+);