Generally we use getNameOfDeclaration or something like that to avoid duplicating the diagnostic. It'll fill it in with something like (anonymous) or (default).

@DanielRosenwasser Thanks for the feedback 👍. Actually, getHeritageClauseVisibilityError uses it

and it returns undefined for the case

export default class extends Foo {}

Based on the type definition, a name can be undefined, however, that case was not handled in getHeritageClauseVisibilityError.

For that reason, TS crashes because it uses diagnostic messages with two arguments, however, receive only one.

Do you propose to replace the missed name by creating Identifier with the(anonymous) name instead of using a new diagnostic message? I think we can do it, just need to create a new Identifier and change the logic to getting text because a new Identifier will not be present in the source file.

Actually I think it's fine, especially since functions have the same diagnostic.

I actually realized that the test might need to be changed to use at least one .js file because of #39617...