FIX: Don't migrate custom emojis that are no longer valid.

* Warn about failed migration in logs.

app/jobs/onceoff/migrate_custom_emojis.rb

@@ -3,7 +3,6 @@ module Jobs
     def execute_onceoff(args)
       return if Rails.env.test?
 
-      CustomEmoji.transaction do
       Dir["#{Rails.root}/#{Emoji.base_directory}/*.{png,gif}"].each do |path|
         name = File.basename(path, File.extname(path))
 
@@ -17,9 +16,13 @@ module Jobs
           )
 
           if upload.persisted?
-              CustomEmoji.create!(name: name, upload: upload)
+            custom_emoji = CustomEmoji.new(name: name, upload: upload)
+
+            if !custom_emoji.save
+              warn("Failed to create custom emoji '#{name}': #{custom_emoji.errors.full_messages}")
+            end
           else
-              raise "Failed to create upload for '#{name}' custom emoji"
+            warn("Failed to create upload for '#{name}' custom emoji: #{upload.errors.full_messages}")
           end
         end
       end
@@ -30,6 +33,9 @@ module Jobs
         post.rebake!
       end
     end
+
+    def warn(message)
+      Rails.logger.warn(message)
     end
   end
 end