By the way, I guess if the problem arises like that, it's because it might be hard to distinguish both situations at the interpreter level, but if it was possible, it would be the best solution to have a different error message (even if I understand we should be very careful with the idea of changing the exception type, even in this case).

I mean : Eric shown an equivalent error, but both are only equivalent at the present discrimination level of the interpreter & language grammar.  I understand that distinguishing both those semantically different situation might be opening the Pandora box and it might be a bad idea... or not.

The point is that, if ever both those situations were in some way distinguishable, then... well... we certainly have no idea of how much code confronted with this specific situation AND treated it with exception handling, BUT, we might make the assumption that a frequent confrontation with this case would then already have been raised before, and consequently, it might be relevant, at least to keep it in mind for a future evolution (4.0) of the language.