From: #586 (comment)

The task process_item_deletion should be improved with a try/catch block around the default_storage.delete(item.file_key) instruction. So it handles case were the file does not exists on the object storage.

Also mind to add the call to process_item_deletion.delay(item.id) in the clean_pending_items.py, so we make sure to remove eventual existing files from the storage.