Thank you, Antoine, you make a good point.

In my example, I am suppressing the warning, which, I agree isn't a good idea.

In my real life usage, I was getting an unexpected exception in a callback in code written by another person. I wanted not to suppress the warning, but to turn it into an exception to help trace the cause.

Thinking about this further, (if it was a warning, as I suggest,) I now believe that would raise that exception into the garbage collector which might have some unpredictable consequences. I have rejected my own Issue for this reason.

I maintain that the current solution isn't terribly helpful. Getting this output to stderr is neither helpful to me, in development (i.e. nothing in the error indicated it was related to the weakref functionality) nor my users in production (fortunately the problem was caught before then!)

However, I concede my proposal isn't the right solution.

Thank you again for your comment.