I just did a spot check of the CommonsNotifier and found https://en.wikipedia.org/wiki/Talk:Basketball#A_Commons_file_used_on_this_page_has_been_nominated_for_deletion. That links to a deletion request page which was never created, since the user only added {{delete}}, but never created the DR page.
The bot should perhaps check if the deletion page exists before posting a link to it ("Participate in the deletion discussion at the nomination page."). If it does not exists, perhaps just write "Participate in the deletion discussion at Wikimedia Commons." or something, since linking to a non-existing page could cause a non-Commons user to believe that they should create that page to start a discussion. Or perhaps not send out a message at all, since a deletion request hasn't actually been made until the DR page has been created.
Sorry if I'm not expressing myself clearly, English is a second language.
Problem:
Sometimes images are mistakenly tagged with deletion notices (or a vandal does it) or it is a case of a very obvious copyright violation or such in which case a discussion is not necessary. In these cases, the nomination page for a file deletion is not created. A nomination page for a file deletion is required for the deletion request to be officially considered.
Example 1, nomination page
Example 2, nomination page
Proposed solution:
Do not send out a message if the nomination page does not exist. Skip it from the queue. The chances that it is a legitimate deletion request is low and the template might be reverted or the image might be removed before the bot gets to post about it.