unhelpful error message for ValueOf[N] when no singleton available for N (bounded by singleton)

Compiler version

3.2.0-RC1

Minimized code

import scala.compiletime.*

class Vec[N <: Int & Singleton] :
  private val xs: Array[Double] = Array.ofDim[Double](summon[ValueOf[N]].value)

Output

No singleton value available for N.

Expectation

My expectation is that the Singleton bound makes ValueOf realize that N is a singleton. But I am no expert, and the fact that https://github.com/lampepfl/dotty/issues/8257 was closed makes me wonder. But then my expectation would be to get an error message that is clearer.

A bit more detail at https://users.scala-lang.org/t/how-do-i-compute-type-level-m-n/8715/2

[som-snytt]

I think I tried to make implicitNotFound show an addendum; maybe that was for overrides?

https://github.com/scala/scala/pull/8280

[SethTisue]

There’s a broader design question here, which is: when a custom implicitNotFound message is available, perhaps it would be nicer if the compiler showed both the custom message, and the more general message that indicates that implicit search failed, and what type is what looking for?