Fix "Cache captureSets of CaptureRefs only at phase cc"

Author: odersky

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -2052,14 +2052,13 @@ object Types {
 
     def captureSetOfInfo(using Context): CaptureSet =
       if ctx.runId == myCaptureSetRunId then myCaptureSet
-      else if (myCaptureSet eq CaptureSet.Pending)
-        || ctx.phase != Phases.checkCapturesPhase then CaptureSet.empty
+      else if myCaptureSet eq CaptureSet.Pending then CaptureSet.empty
       else
         myCaptureSet = CaptureSet.Pending
         val computed =
           if isRootCapability then singletonCaptureSet
           else CaptureSet.ofType(underlying)
-        if underlying.isProvisional then
+        if ctx.phase != Phases.checkCapturesPhase || underlying.isProvisional then
           myCaptureSet = null
         else
           myCaptureSet = computed