File uploading using ajax call in laravel 5.4

In my application I need to upload a cover image for a dish.

Here's my AJAX call:

$('#addDishForm').submit(function(e) {
    e.preventDefault();
    var el = $(this);
    var formAction = el.attr('action');
    var formValues = el.serialize();
    console.log(formValues);

    $.ajax({
        type: 'POST',
        url: '/admin/menu',
        data: new FormData(el[0]),
        success: function (data) {
            console.log(data);
        },
        error: function(data) {
            console.error(data);
        }
    });
}); 

I have an error as a result return from controller in console.

Uncaught TypeError: Illegal invocation

What is the workaround?

Here is the controller's method:

public function store(Request $request)
{
    if($request->hasFile('cover_image'))
    {
        return response()->json([ 'success' => true, 'message' => 'File exists' ]);
    }
    else 
    {
        return response()->json([ 'success' => false, 'message' => 'File doesn\'t exist' ]);
    } 
}

A route:

Route::middleware('auth')->prefix('/admin')->namespace('Admin')->group(function () {
    // other routes ...
    Route::post('/menu', 'MenuController@store');
    // other routes ...
});

After the response in console I can the that success is false.

Here's the form:

{!! Form::open([ 'method' => 'POST', 'enctype' => 'multipart/form-data', 'id' => 'addDishForm' ]) !!}
    // other form controls ...
    
    // other form controls ...
{!! Form::close() !!}

via Chebli Mohamed