Handle NoType in disjointnessBoundary

Author: dwijnand

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

@@ -2863,6 +2863,8 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
         disjointnessBoundary(tp.effectiveBounds.hi)
       case tp: ErrorType =>
         defn.AnyType
+      case NoType => // ParamRef#superTypeNormalized can return NoType
+        defn.AnyType
     end disjointnessBoundary
 
     (disjointnessBoundary(tp1), disjointnessBoundary(tp2)) match