module: fix initial ModuleWrap with non-string source

lib/internal/modules/esm/translators.js

@@ -85,7 +85,7 @@ translators.set('module', async function moduleStrategy(url) {
     source, { url, format: 'module' }, defaultTransformSource));
   maybeCacheSourceMap(url, source);
   debug(`Translating StandardModule ${url}`);
-  const module = new ModuleWrap(url, undefined, source, 0, 0);
+  const module = new ModuleWrap(url, undefined, `${source}`, 0, 0);
   moduleWrap.callbackMap.set(module, {
     initializeImportMeta,
     importModuleDynamically,

test/fixtures/es-module-loaders/loader-invalid-transform-source.mjs

@@ -0,0 +1,7 @@
+export function transformSource() {
+  return {
+    source: {
+      boom: true
+    }
+  };
+}

test/message/esm-invalid-transform-source.mjs

@@ -0,0 +1,4 @@
+// Flags: --experimental-loader ./test/fixtures/es-module-loaders/loader-invalid-transform-source.mjs
+// Fixes: https://github.com/nodejs/node/issues/33441
+import '../common/index.mjs';
+import 'fs';

test/message/esm-invalid-transform-source.out

@@ -0,0 +1,9 @@
+(node:*) ExperimentalWarning: --experimental-loader is an experimental feature. This feature could change at any time
+(Use `node --trace-warnings ...` to show where the warning was created)
+file:///*/test/message/esm-invalid-transform-source.mjs:1
+[object Object]
+        ^^^^^^
+
+SyntaxError: Unexpected identifier
+    at Loader.moduleStrategy (internal/modules/esm/translators.js:*:*)
+    at async link (internal/modules/esm/module_job.js:*:*)