PostgreSQL & Node.js - Invalid input syntax for integer

When I send request for user registration or login, in 80% cases it works correctly - but in some cases it throws an error like this:

ERROR: invalid input syntax for integer 'foo@bar.com'

It throws this error because request is going to get route and then is interpreted as parameter for getting individual items.

On front-end I'm using axios for requests and there is some actions from redux:

export function userSignupRequest(userData) {
  return dispatch => {
    return axios.post(`${API_URL}/users`, userData);
  }
}

export function login(data) {
  return dispatch => {
    return axios.post('http://vetguide.co/auth/login', data).then(res => {
      const token = res.data.token;
      localStorage.setItem('jwtToken', token);
      setAuthorizationToken(token);
      dispatch(setCurrentUser(jwtDecode(token)));
    });
  }
}

Also there are authorization headers:

import axios from 'axios';

export default function setAuthorizationToken(token) {
  if (token) {
    axios.defaults.headers.common['Authorization'] = `Bearer ${token}`;
  } else {
    delete axios.defaults.headers.common['Authorization'];
  }
}

I can not figure out this error, it's so confusing...

via Mihajlo Jovanović