title: Getting error second time getting to page with ng2-dragula
body: <p>I am trying to prevent user to move first element of <code>dragulaService</code>, the code works first time without any errors, but when I leave this page and then open it again, I'm getting error.</p>
  
  <p>The code that is causing the error:</p>
  
  <pre><code>constructor(public service:SmartTablesService, private dragulaService:DragulaService) {
      dragulaService.setOptions('nested-bag', {
        revertOnSpill: true,
        moves: function (el:any, container:any, handle:any):any {
          if (handle.className === 'sorting-table-title') {
            return false;
          } else {
            return true;
          }
  
        }
      });
  </code></pre>
  
  <p>The error is:</p>
  
  <blockquote>
    <p>error_handler.js:48 EXCEPTION: Uncaught (in promise): Error: Error in ./SortTableComponent class SortTableComponent_Host - inline template:0:0 caused by: Bag named: "nested-bag" already exists.
    Error: Bag named: "nested-bag" already exists.
    at DragulaService.add (<a href="http://platform.local:8080/3.chunk.js:1070:19" rel="noreferrer">http://platform.local:8080/3.chunk.js:1070:19</a>)
    at DragulaService.setOptions (<a href="http://platform.local:8080/3.chunk.js:1099:24" rel="noreferrer">http://platform.local:8080/3.chunk.js:1099:24</a>)
    at new SortTableComponent (<a href="http://platform.local:8080/3.chunk.js:1311:24" rel="noreferrer">http://platform.local:8080/3.chunk.js:1311:24</a>)</p>
  </blockquote>