console.error: "uncaught", "at rootSaga at loginFlow ...

I’m trying to implement a really basic login skeleton similar to what is detailed in the docs. Mine is a little simpler since in my UI there will be no way for the user to send a login action before the login actually occurs. But, I am working in react-native if that makes any difference.

So I have a button right now that dispatches an action with a mock payload. This action is recognized by the reducer, so it is firing. But when it hits the saga for some reason I get the following error:

Here is my saga code:

function* authorize(email, password) {
  // just returns a fake token for now
  const session = 'fake'
  yield console.log('in authorize');
  yield put({type: types.LOGIN_SUCCESS, session});
  return session;
}

function* loginFlow() {
  while (true) {
    const submit_action = yield take(types.LOGIN_SUBMITTED);
    const email = submit_action.payload.email;
    const password = submit_action.payload.password;
    yield console.log(email);
    const session = yield call(authorize, email, password);
    // After we're logged in, only thing we can do is log out
    // TODO: figure out what to actually do here?
    if (session) {
      yield take('LOGOUT')
    }

  }
}

export default function* rootSaga() {
  yield fork(loginFlow);
}

Also, here is my saga initialization code:

// saga initialization
const sagaMiddleware = createSagaMiddleware();
const store = applyMiddleware(sagaMiddleware)(createStore)(reducer);
sagaMiddleware.run(rootSaga).done.catch((error) => console.warn(error));

The exception seems to occur before the console.log(email) in loginFlow. I’m not really sure how this is happening. Any help on the issue would be appreciated.

[rclai]

Is there any way to make these exception errors more helpful? It doesn’t matter what kind of exception is raised, but every kind of error looks exactly like OPs screenshot. There is no way to see where the error originates from. I’m using redux-saga in a React Native context.

[Andarist]

Probably one of your dispatched actions throw, one of loginSuccess, loginFailure.

It may be in you reducer, I see there is a replaceAtIndex function in your call stack. Maybe it doesnt receive correct arguments? Try to wrap your actions in:

try {
  // ... regular action code
} catch (e) {
  debugger
}

and your should find the mistake within minutes.

Hope you catch it!