I assume this is something where the __next__() method on your iterator class calls next() on some other iterator and accidentally doesn't catch the StopIteration coming out of it (or, more likely, this happens several calls deep, making it more interesting to debug).

That particular problem is not unique to __next__ and StopIteration -- the same thing can (and does!) happen with __getitem__ and KeyError or IndexError, and with __getattr[ibute]__ and AttributeError.

In all these cases I think there isn't much we can do apart from adding lint rules. If you are writing __next__ as a method on an iterator class, one way or another you are going to have to raise StopIteration when there isn't another element, and similarly __getitem__ has to raise KeyError or IndexError, etc.

In the generator case, we have a better way to signal the end -- a return statement (or falling off the end). And that's why we can even contemplate doing something different when StopIteration is raised in the generator.

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