test: cover worker throwing primitive values

A worker that throws a non-Error value (string, number, bigint,
boolean, null, undefined) surfaces that value on the parent's
'error' handler. This was reported as a wrapped ERR_UNHANDLED_ERROR
and is now correct, but had no regression coverage.

Refs: #35506
Signed-off-by: dobbydobap <varshitha.kolupuri@gmail.com>

Author: dobbydobap

test/parallel/test-worker-error-primitive.js

@@ -0,0 +1,25 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { Worker } = require('worker_threads');
+
+const cases = [
+  { code: 'throw "boom";', value: 'boom' },
+  { code: 'throw 42;', value: 42 },
+  { code: 'throw 7n;', value: 7n },
+  { code: 'throw true;', value: true },
+  { code: 'throw null;', value: null },
+  { code: 'throw undefined;', value: undefined },
+  { code: 'throw Symbol.for("a");', value: Symbol.for('a') },
+];
+
+for (const { code, value } of cases) {
+  const worker = new Worker(code, { eval: true });
+  worker.on('message', common.mustNotCall());
+  worker.on('error', common.mustCall((err) => {
+    assert.strictEqual(err, value);
+  }));
+  worker.on('exit', common.mustCall((exitCode) => {
+    assert.strictEqual(exitCode, 1);
+  }));
+}