Added fix to email input focus behaviour when there is an error

Currently when users makes mistake or leaves the email input empty the focus returns to the begining of the page causing the user to have to travel across multiple elements to be able to re-enter their email. With this fix the focus goes back to the email input element.

web/cobrands/fixmystreet/fixmystreet.js

@@ -1512,12 +1512,23 @@ $.extend(fixmystreet.set_up, {
     });
     $('body').on('click', '#alert_email_button', function(e) {
         e.preventDefault();
+
+        var emailInput = $(this).closest('.js-alert-list').find('input[type=email]');
+        var emailValue = emailInput.val();
+
+        if (jQuery.validator.methods.notEmail.call({ optional: function() { return false; } }, emailValue)) {
+            emailInput.focus();
+            return;
+        }
+
         var form = $('<form/>').attr({ method:'post', action:"/alert/subscribe" });
         form.append($('<input name="alert" value="Subscribe me to an email alert" type="hidden" />'));
+
         $(this).closest('.js-alert-list').find('textarea, input[type=email], input[type=text], input[type=hidden], input[type=radio]:checked').each(function() {
             var $v = $(this);
             $('<input/>').attr({ name:$v.attr('name'), value:$v.val(), type:'hidden' }).appendTo(form);
         });
+
         $('body').append(form);
         form.trigger('submit');
     });