Exceptions in N-API Init are not reported during require() call

[fluggo]

• Version: v9.8.0 (Docker [email protected] image)
• Platform: Linux a5d5c8becf83 4.4.0-104-generic src: fix unaligned access in ucs2 string encoder #127-Ubuntu SMP Mon Dec 11 12:16:42 UTC 2017 x86_64 GNU/Linux
• Subsystem: addons n-api

When using N-API, if an exception is thrown during the module's Init, it is not reported during the require() call and might not be reported at all.

If you modify the N-API hello world sample code to throw an error during Init:

 napi_value Init(napi_env env, napi_value exports) {
   napi_status status;
   napi_property_descriptor desc = DECLARE_NAPI_METHOD("hello", Method);
   status = napi_define_properties(env, exports, 1, &desc);
   assert(status == napi_ok);
-  return exports;
+  napi_throw_error(env, "CODE", "Test error");
+  printf("Ran error code\n");
+  return nullptr;
 }

...the error itself is not thrown until the hello() method call:

root@a5d5c8becf83:/app/pure-napi# node hello.js
Ran error code
/app/pure-napi/hello.js:3
console.log(addon.hello()); // 'world'
                  ^

Error [CODE]: Test error
    at Object.Module._extensions..node (module.js:678:18)
    at Module.load (module.js:561:32)
    at tryModuleLoad (module.js:501:12)
    at Function.Module._load (module.js:493:3)
    at Module.require (module.js:593:17)
    at require (internal/module.js:11:18)
    at bindings (/app/pure-napi/node_modules/bindings/bindings.js:76:44)
    at Object.<anonymous> (/app/pure-napi/hello.js:1:94)
    at Module._compile (module.js:649:30)
    at Object.Module._extensions..js (module.js:660:10)

Further, if the method is not called, the error isn't reported at all.

[fluggo]

Verified that it does work when not using N-API. In a pure V8-only addon:

void Init(Handle<Object> exports) {
  Isolate* isolate = Isolate::GetCurrent();
  exports->Set(String::NewFromUtf8(isolate, "hello"),
      FunctionTemplate::New(isolate, Method)->GetFunction());
  isolate->ThrowException(String::NewFromUtf8(isolate, "Test error"));
}

I get:

root@a5d5c8becf83:/app/pure-node# node hello.js

module.js:678
  return process.dlopen(module, path.toNamespacedPath(filename));
                 ^
Test error

[richardlau]

cc @nodejs/n-api

[gabrielschulhof]

There are actually several places where we should check for exceptions resulting from calls into the N-API addon.