[Issue 21298] Missing error when overriding interface method without in contract with class method with contract

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21298

--- Comment #5 from anonymous4 <dfj1esp02 at sneakemail.com> ---
The error is that the contract of the subtype is stricter than the contract of
the supertype.

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