In React, how do I handle errors coming back from the server?

I have a signup form in my app that submits data to the my backend server, with a Redux thunk that calls my API and handles the returned data. Right now it only actually catches errors that occur within React/Redux. If the server returns an error, my action creator thinks the error is part of a user record and authenticates my "user", even if I submitted an empty form.

My handleSubmit function (extracted from my AuthForm component):

 const handleSubmit = e => {
    e.preventDefault();
    onAuth(formType, state);
    setState(formType === 'login' ? initialStateLogin : initialStateSignup);
    history.push("/");
  }

My onAuth function (which maps to my authUser Redux thunk):

export function authUser(type, userData) {
  return dispatch => {
      return apiCall("post", `/users/${type}`, userData)
        .then(({ jwt, ...user }) => {
          console.log(jwt, user)
          localStorage.setItem("jwtToken", jwt);
          setAuthorizationToken(jwt);
          dispatch(setCurrentUser(user));
          dispatch(removeError());
        })
        .catch(err => {
          console.log(err);
          dispatch(addError(err.message));
        });
  };
}

My apiCall helper function:

export async function apiCall(method, path, data) {
  try {
    const res = await axios[method.toLowerCase()](`${API_PATH}${path}`, data);
    return res.data;

  }
  catch(err) {
    console.log(err);
    return err.response.data || "An unknown error occurred";
  }
}

If I submit an empty form, my Redux state looks like this:

currentUser {
  isAuthenticated: true,
  user: {
    error: {
      message: "Could not create user. Please modify parameters and try again."
    }
 }
}