Looks like a bug to me as well. Simpler example:
➜ class a {}; { sub a {42}; say a }
(a)
➜ class a {}; { sub a {42}; say a() }
Method 'shortname' not found for invocant of class
'Perl6::Metamodel::CoercionHOW'
in block <unit> at -e line 1 (a)
