Perhaps it would be an idea to include the error message:
Cannot invoke object with invocation handler in this context in sub getgrgid at b line 11 in block <unit> at b line 15 and the perl6 --version This is Rakudo version 2016.12-118-g3baffe7 built on MoarVM version 2016.12-21-g3dc5647 implementing Perl 6.c.
