RakuAST: ensure symbols accessed by BEGIN time code are resolved

Generating a compile-time-value may need some lookups to have been
resolved.

src/Raku/ast/code.rakumod

@@ -264,6 +264,7 @@ class RakuAST::Code
                     elsif $name ne '$_' { #TODO figure out why we specifially don't declare $_ in ExpressionThunks
                         my $decl := $!resolver.resolve-lexical-constant($name);
                         if $decl {
+                            $decl.IMPL-CHECK($resolver, $context, 1); # Ensure any required lookups are resolved
                             my $value := $decl.compile-time-value;
                             $context.ensure-sc($value);
                             $var := QAST::WVal.new(:$value);