Can you help me figure out $resource and server response?

Question

Angular

I make comments on articles (Two related schemas DiscussSchema and CommentSchema).
Made a service

angular.module('discusses').factory('Comments', ['$resource',
  function($resource) {
    return $resource('api/discusses/comments', 
    {
      update: {
        method: 'POST'
      }
    });
  }
]);

,
In the angular controller

var CommentResource = Comments;
$scope.addComment = function(){
    var commentRes = new CommentResource();
    console.log(commentRes);
    commentRes.discuss_id = $stateParams.discussId;
    commentRes.body = $scope.commentData.body;
    commentRes.user = user;

    commentRes.$save(function(result){
      
    });
};

Everything is displayed in the console normally. id, user as object, all is well.
In server parties I write

module.exports = function (app) {
    var disсusses = require('../controllers/disсusses.server.controller');
    var disсussesPolicy = require('../policies/disсusses.server.policy');
app.route('/api/disсusses/comments').all(disсussesPolicy.isAllowed)
            .post(disсusses.addcomments)
            .get(disсusses.listall);

in the server controller I write

exports.addcomments = function(req,res, next){
    console.log('server addcomments');
  };
exports.listall = function(req,res,next){
    console.log('sever lisall');
};

But when I click addComment() I get

GET http://localhost:3000/server-error 500 (Internal Server Error)

Those. something is sent there. And the question is why GET? $save sort of goes like POST
What's going on and who's to blame?

Answer 1

most likely the server redirected you to server-error, and the redirect request was already GET

Answer 2

If there was a redirect (and it almost certainly was), then you can see in the developer panel all the requests that the browser sent, in particular, the request that received the redirect command in response.
And so - 500 error is sent manually somewhere in the application, most likely, so you need to first find out where exactly. Most likely some middleware like bodyparser failed to process the request. In general, it is strange that there was a redirect to /server-error. In a good way, an error should be generated not on a redirect, but directly on the page on which it occurred. Well, take a look at the application console, there may also be something useful there.

Answer 3

Then the next question. Now I make embedded comments.
Angular :

angular.module('discusses').factory('Discusses', ['$resource',
  function($resource) {
    return $resource('api/discusses/:discussId', { discussId: '@_id'
    }, {
      update: {
        method: 'PUT'
      }
    },
       {
       	addcomment: {
       		method: 'PUT'
       	}
    };

In the controller

$scope.addComment = function() {
      var discuss = new Discusses();
      var content = $scope.content;

      discuss.addcomment(function() {
        discuss.comments.push(content);
        $location.path('discusses/' + discuss._id);
    
      }, function(errorResponse) {
        $scope.error = errorResponse.data.message;
      });
    };

In case
discuss.addcomment, including with $
issues

TypeError: undefined is not a function
    at Scope.$scope.addComment

If I change it to $update, then everything works (well, in fact, it turns out crap, but the request gets to the api server)