The response code section is not a complete list of all of the response codes that might deliver, but rather a selection of the most common response codes that deliver.
The 142 error error (Can’t favorite Tweets of protected users you aren’t following) might be a user who has gone private since you favorited their Tweet, so you can’t unfavorite it due to this protection.
The 136 is similar, but relates to being blocked instead of being protected.
As for the 144 when the Tweet is still active, I’m going to have to have a chat about this with a colleague who is currently out on vacation. I’ll get back to you when I can on this situation.