Set initial stop_id to empty string to avoid undefined after #! in URL

 index.js

@@ -8,7 +8,7 @@
var language = 'en';
var lang_select = document.getElementById('lang-select');

var stop_id;
var stop_id = '';
var stop_name = document.getElementById('stop-name');
var stop_name_form = stop_name.form;
var stop_name_autocomplete = document.getElementById('stop-name-autocomplete');