tinymce mceRemoveControl NS_ERROR_UNEXPECTED: Component returned failure code

Im not sure if its considered a bug, but this is annoying for me.
When i ran mceRemoveControl command to remove a already destroyed tinymce on a textarea,
i get NS_ERROR_UNEXPECTED.

After googling around with not much result, ive decided to dig into the source code ,
and finally found a solution.
Instead of calling directly mceRemoveControl, call this tinyMCE.remove(tinyMCE.getInstanceById()):

var oInstance = tinyMCE.getInstanceById("txtContent");
if (oInstance) {
  if (oInstance.isHidden()) tinyMCE.remove(oInstance);
  tinyMCE.execCommand('mceRemoveControl', true, "txtContent");
}
tinyMCE.execCommand('mceAddControl', true, "txtContent");

tinyMCE.remove(tinyMCE.getInstanceById("txtContent"))

tinyMCE.remove(tinyMCE.getInstanceById("txtContent"))