Silence a debug println

Currently, when running testCompilation i1286, the following always gets
printed:

error while transforming method splitAt
error while transforming method tuple2ToZippedOps

It seems that the associated error gets caught and handled, so we shouldn't
print this message.

Author: abgruszecki

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

@@ -791,7 +791,7 @@ object Denotations {
       val currentPeriod = ctx.period
       val valid = myValidFor
 
-      def signalError() = println(s"error while transforming $this")
+      def signalError() = () //println(s"error while transforming $this")
 
       def assertNotPackage(d: SingleDenotation, transformer: DenotTransformer) = d match
         case d: ClassDenotation =>