It was supposed to check only function types...
Also note that it's probably impossible
to write a simpler test right now,
because we have a massive problem that
we ignore `FirTypeRef`s with `null`
sources despite having a dedicated
family of checkers for them
specifically. This will be fixed
separately as KT-65647.
^KT-65584 Fixed
^KT-65647
The diagnostic target source element
type was changed to prevent crash due
to `checkPsiTypeConsistency()` in
`duplicateParameterNameSimplified.fir.kt`
^KT-65584