Fix RT #125689.

For some reason the lookup with $*W.find_symbol in apply_trait doesn't look for
X::Inheritance::UnknownParent but Inheritance::UnknownParent in 'class X is
nosuchtrait { }', presumably because it happens 'inside' package X. Changing
the lookup to only look inside the setting loops infinitely when compiling the
setting.  The empty (but commented) CATCH prevents this.

src/Perl6/World.nqp

@@ -2743,13 +2743,21 @@ class Perl6::World is HLL::World {
             CATCH {
                 $ex := $_;
                 my $payload := nqp::getpayload($_);
-                if nqp::istype($payload, self.find_symbol(["X", "Inheritance", "UnknownParent"])) {
+                if nqp::istype($payload, self.find_symbol(["X", "Inheritance", "UnknownParent"], :setting-only)) {
                     my @suggestions := self.suggest_typename($payload.parent);
                     for @suggestions {
                         $payload.suggestions.push($_)
                     }
                 }
                 $nok := 1;
+                CATCH {
+                    # we only get here if we 
+                    # 1) don't have a setting 
+                    # 2) look # for X::Inheritance::UnknownParent while sorta-inside X,
+                    #    e.g. "class X is nosuchtrait { }" 
+                    # building the setting loops infinitely without this CATCH
+                    # block when calling find_symbol with :setting-only
+                }
             }
             CONTROL {
                 if nqp::getextype($_) == nqp::const::CONTROL_WARN {