Harden tryReduce

When compiling kind-incorrect code in neg/anykind3.scala, substParams fails with
an index-out-bounds exception. It is called from tryReduce via instantiate. We
know there are several scenarios where this can happen - Sandro has detected
a couple of others. This commit avoids the problem by aborting the reduce
if there is an index out of bounds.

Author: odersky

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

@@ -367,7 +367,9 @@ class TypeApplications(val self: Type) extends AnyVal {
                 case _ => false
               }
             }
-            if ((dealiased eq stripped) || followAlias) dealiased.instantiate(args)
+            if ((dealiased eq stripped) || followAlias)
+              try dealiased.instantiate(args)
+              catch { case ex: IndexOutOfBoundsException => AppliedType(self, args) }
             else AppliedType(self, args)
           }
           else dealiased.resType match {