title: ag-Grid row not deleting
body: <p>I am trying to delete a row from my ag-Grid like so:</p>
  
  <pre><code>let alertRow : RowNode = this.gridApi.getRowNode(rowIndex);
  console.log(alertRow);
  this.gridApi.updateRowData({remove: [alertRow]});
  </code></pre>
  
  <p>It gives me this error:</p>
  
  <blockquote>
    <p>ag-Grid: could not find data item as object was not found </p>
  </blockquote>
  
  <p>I can see in console the <code>RowNode</code> is the correct node and exists.  I am also able to use <code>updateRowData()</code> to add new rows in fine but trying to remove gives this error.</p>
  
  <p>I am using ag-Grid in Angular 6 component.</p>
  
  <p>Why is removing not working?</p>