Nope never, but I’ve from what I’ve read most of the older articles/books written on the subject do give warnings like this. It varies from being sure you kill the servitor after your done with it, to being careful to give them plenty of food from a source outside of the personal self to prevent them from becoming parasitic.
I think the only real reasons something like this would happen would be either
a.) insufficient energy source, or
b.) somehow abusing the fck of the servitor ( I mean they are spirits too, right? so maybe?)
c.) not programming the servitor sufficiently. For example I program all of mine that they need to be summoned to take new orders from whomever they belong to- simply thinking about giving a task or making a change to the servitor Will not work, period- because then we might have times we are contemplating things, and wouldn’t it be a shame if the servitor took the thoughts as orders, rather than waiting- we might change our mind or any number of things.
I also build all of my servitors with a kill switch unless I’m told the by they mage they do not want one, but I’ve never had anyone use it yet.
I would feel like I failed if they needed to though, because I try to make servitors thst are going to be around and effective for a long time, not for a short duration types of magic/single tasks.