Prevent an object from being "converted to shareable"

[yolpsoftware]

It seems one of my helper objects (a singleton that provides a few frequently-used methods) is "converted to a shareable" in one of the worklets of my app. Afterwards, I receive lots of warnings of the type "Tried to modify key ... of an object which has been already passed to a worklet."

I have tried to find the problematic worklet, but no luck so far. This object should not be used in a worklet, and I can't find the worklet that does so.

Is there a way to mark an object as "should not be converted to shareable", such that I get an error the moment it gets converted? Is there some other way to find the culprit?