SuspendException in posttyper with -language:experimental.into

[propensive]

Compiler version

This issue is present in the latest main, and was introduced by 32f5a1747dbcc9a2f213b8bfcfa88865163ca43b (Compute non-experimental top-level definition from symbols, @nicolasstucki).

Minimized code

a.scala:

val value = opaques.x.get

b.scala:

import scala.quoted.*

trait Op:
  extension (left: opaques.X)
    def get: Any = ???

object opaques:
  opaque type X = Unit
  val x: X = ()

  def typeclass(using Quotes): Expr[Op] = '{???}

  object X:
    transparent inline given Op = ${typeclass}

Compile with:

> scalac -language:experimental.into a.scala b.scala

Output (click arrow to expand)

  unhandled exception while running posttyper on b.scala

  An unhandled exception was thrown in the compiler.
  Please file a crash report here:
  https://github.com/scala/scala3/issues/new/choose
  For non-enriched exceptions, compile with -Yno-enrich-error-messages.

     while compiling: b.scala
        during phase: posttyper
                mode: Mode(ImplicitsEnabled)
     library version: version 2.13.12
    compiler version: version 3.5.0-RC1-bin-SNAPSHOT-git-32f5a17
            settings: -language List(experimental.into)

Exception in thread "main" dotty.tools.dotc.CompilationUnit$SuspendException

Note that this is the entire output: the exception is not actually show.