Firebase: return caught error from signInWithEmailAndPassword

Question

I am using firebase with Email+Password auth provider. Correct credentials case works as expected. My problem is that if credentials are wrong, error is caught, but I don't know how to pass this information back.

I am connecting dispatch from redux store with mapDispatchToProps.

const mapDispatchToProps = (dispatch) => ({
  startLogin: (email, password) => dispatch(startLogin(email, password))
});

Then I just call this action with credentials from my component and if undefined was returned (error thrown), I set errors.

startLogin(email, password).then((data) => {
  if (!data) {
    setErrors({ login: 'Wrong credentials' });
  }
});

My action look like this.

export const startLogin = (email, password) => {
  return firebase.auth().signInWithEmailAndPassword(email, password).catch((err) => {
    console.log(err);
  });
};

This works, but console shows POST 400 error which I would like to avoid.