Fix an error when file_file_size is nil in tootctl media remove (#14657)

lib/mastodon/media_cli.rb

@@ -31,7 +31,7 @@ module Mastodon
       processed, aggregate = parallelize_with_progress(MediaAttachment.cached.where.not(remote_url: '').where('created_at < ?', time_ago)) do |media_attachment|
         next if media_attachment.file.blank?
 
-        size = media_attachment.file_file_size + (media_attachment.thumbnail_file_size || 0)
+        size = (media_attachment.file_file_size || 0) + (media_attachment.thumbnail_file_size || 0)
 
         unless options[:dry_run]
           media_attachment.file.destroy