Callback exception catch and rethrow

[bsrdjan]

How to catch and rethrow callback exceptions, replacing following Nan block with Napi?

Nan::TryCatch try_catch;

Local<Function> callback = Nan::New<Function>(baton->callback);
Nan::Call(callback, Nan::New<Object>(), 2, argv);

if (try_catch.HasCaught())
{
    Nan::FatalException(try_catch);
}

[NickNaso]

Hi @bsrdjan,
you could take a look at this example from the test case.
https://github.com/nodejs/node-addon-api/blob/master/test/error.cc#L34
We are working on error handling documentation. I hope that it will be available very soon.

[bsrdjan]

Hi @NickNaso,

thank you very much for examples. I checked also issues N-API #235 and nodejs #15371 and tried following:

// AsyncWorker...
void OnOK()
{
    client->alive = (client->errorInfo.code == RFC_OK);
    try
    {
        if (!client->alive)
        {
            Callback().Call({wrapError(&client->errorInfo)});
        }
        else
        {
            Callback().Call({});
        }
    }
    catch (const Error &e)
    {
        //Napi::EscapableHandleScope scope(Callback().Env());
        printf("rethrow...\n");
        e.ThrowAsJavaScriptException();
    }
}

// test javascript
function test(err) {
    console.log('invoked');
    const m = 1;
    const n = m + z; // <- exception
}

try {
    test();
} catch (ex) {
    console.log('Caught js');
    assert(ex.name === 'ReferenceError');
    assert(ex.message === 'z is not defined');
    assert(ex.stack.length > 0);
}

try {
    client.connect(test);
} catch (ex) {
    console.log('Caught n-api');
}

The test output is not as expected, the exception is rethrown from AsyncWorker but not get cought in JS. Instead of exception, I would expect seeing Caught n-api in log:

// test output
invoked
Caught js
invoked
rethrow...
/home/www-admin/src/node-rfc/exp/exception.js:15
    const n = m + z;
                  ^
ReferenceError: z is not defined

Any ideas what could be wrong here?

Platform is Linux, with binding.gyp config

            "cflags!": ["-fno-exceptions"],
            "cflags_cc!": ["-fno-exceptions"],

            "defines": [
                "SAPwithUNICODE",
                "SAPwithTHREADS",
                "NDEBUG",
                "NAPI_CPP_EXCEPTIONS"
            ],

[bsrdjan]

after some more analysis, found the behaviour is standard for JavaScript, no issues with addon.