fixed so animation starts as soon as one pushes the button and animation stops if login failed

public/app/core/controllers/login_ctrl.ts

@@ -102,21 +102,26 @@ export class LoginCtrl {
 
     $scope.login = function() {
       delete $scope.loginError;
+      $scope.loggingIn = true;
 
       if (!$scope.loginForm.$valid) {
         return;
       }
 
-      backendSrv.post('/login', $scope.formModel).then(function(result) {
+      backendSrv
+        .post('/login', $scope.formModel)
+        .then(function(result) {
           $scope.result = result;
 
           if ($scope.formModel.password !== 'admin' || $scope.ldapEnabled || $scope.authProxyEnabled) {
-          $scope.loggingIn = true;
             $scope.toGrafana();
             return;
           } else {
             $scope.changeView();
           }
+        })
+        .catch(() => {
+          $scope.loggingIn = false;
         });
     };