Fixed Moderation Deleting Item Bug

When an item's discussion thread has been deleted before the item has been deleted from the moderation queue and then when you try to delete the item from the moderation queue this error will occur.

Code:

A discussion insert was attempted without the required first message.

XenForo_DataWriter_Discussion->_preSave() in XenForo/DataWriter.php at line 1434
XenForo_DataWriter->preSave() in XenForo/DataWriter.php at line 1373
XenForo_DataWriter->save() in NFLJ/Showcase/DataWriter/Item.php at line 480
NFLJ_Showcase_DataWriter_Item->_updateModerationQueue() in NFLJ/Showcase/DataWriter/Item.php at line 306
NFLJ_Showcase_DataWriter_Item->_postSave() in XenForo/DataWriter.php at line 1397
XenForo_DataWriter->save() in NFLJ/Showcase/ModerationQueueHandler/Item.php at line 73
NFLJ_Showcase_ModerationQueueHandler_Item->deleteModerationQueueEntry() in XenForo/Model/ModerationQueue.php at line 202
XenForo_Model_ModerationQueue->saveModerationQueueChanges() in XenForo/ControllerPublic/ModerationQueue.php at line 74
XenForo_ControllerPublic_ModerationQueue->actionSave() in XenForo/FrontController.php at line 337
XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 134
XenForo_FrontController->run() in xenforo/index.php at line 13