title: Error when calling .processQueue() in Dropzonejs
body: <p>I'm using dropzoneJS in my project. In the <code>addedfile</code> event I've added: </p>
  
  <pre><code>    var csrf = $('input[name=_token]').val();
      $.ajax({
          async: true,                      
          method: 'POST',
          dataType: 'json',
          url: '../public/userfiles',
          data: {"_token": csrf  },
          complete: function(data) {
              var maxsize = 314572800;
              var freesize = maxsize - data.responseJSON;
              if(file.size &gt; freesize){
                  alert('Нямата достатъчно свободно пространсво.');
              }
              else {
                  alert('Успешно качен файл');
                  return Dropzone.prototype.processQueue();         
              }
          }
      });
  </code></pre>
  
  <p>This actually get the summed up sizes of all the uploaded files and checks wheter the currently uploaded file is larger than the 'free space'. I've set on false the autoProcessQueue option in order to make the check. After checking the size I call the function which should proceed the queue. But the last line <code>return Dropzone.prototype.processQueue();</code> gives me an error in the console saying </p>
  
  <p><code>TypeError: this.options is undefined
  parallelUploads = this.options.parallelUploads;</code>
  What could be the case?
  EDIT: 
  <a href="https://i.stack.imgur.com/2lbGJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2lbGJ.png" alt="enter image description here"></a></p>