I think I found another issue with the new type inference:

fun fred(map: Map<String, Any?>) {
    ...
}

fun test() {
    fred(mapOf("a" to { x: Color -> x.grayValue() }, "b" to Color.BLUE))
}

The

{ x: Color -> x.grayValue()}

is marked as an error due to

Type mismatch

Required: Color

Found: (Color) -> UByte

But it compiles and runs fine