checker: fix and improve return stmt error messages

[felipensp]

Fix #17473

[JalonSolov]

This doesn't look correct. You should be able to do return none because of the ? declaration as the return type. You just shouldn't be able to return anything else.

I would expect this particular error to be something like "can only return none from an Option-only return function" or something similar.

[felipensp]

This doesn't look correct. You should be able to do return none because of the ? declaration as the return type. You just shouldn't be able to return anything else.

I would expect this particular error to be something like "can only return none from an Option-only return function" or something similar.

Return none is ok. The problem is the multiple return. This is what I am checking.

[JalonSolov]

Your current error message doesn't say anything about what the problem is...

error: unexpected argument, current function does not return anything

This is incorrect, as it could return none, but it might not return anything (if it succeeded). That's why I suggested an alternative error message, which directly relates to the problem.

[felipensp]

Your current error message doesn't say anything about what the problem is...

error: unexpected argument, current function does not return anything

This is incorrect, as it could return none, but it might not return anything (if it succeeded). That's why I suggested an alternative error message, which directly relates to the problem.

Ah Yes. Agreed.