Fix error reporting inside the setting

without thsi patch, at least r-m always printed the last key for all elements

src/Perl6/World.nqp

@@ -2861,7 +2861,7 @@ class Perl6::World is HLL::World {
         my @err := ['Error while compiling, type ', join('::', $ex_type),  "\n"];
         for %opts -> $key {
             @err.push: '  ';
-            @err.push: $key;
+            @err.push: ~$key;
             @err.push: ': ';
             @err.push: safely_stringify(%opts{$key});
             @err.push: "\n";