[analyzer] confusing text for `implements_non_class`

[incendial]

Hi,

enum Base { first; }

enum Another implements Base { second; }

here implements Base is highlighted with the following message:

And Another is not a class or mixin.

Dart SDK version: 3.9.2 (stable) (Wed Aug 27 03:49:40 2025 -0700) on "macos_arm64"

[bwilkerson]

Yes, this should be fixed.

I would propose special casing enums and producing a problem message along the lines of

Enums can only implement classes and mixins.

The correction message looks fine.