[perl #131623] [BUG] Range + detached method + map with &sub = "Cannot find method 'count' on object of type NQPMu"

[via RT]

# New Ticket Created by  Zoffix Znet 
# Please include the string:  [perl #131623]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=131623 >


A WhateverCode detached map or a &sub undetached map works fine:
    m: ^2 .map: *.say
    rakudo-moar 86e7b2: OUTPUT: «0␤1␤»
    m: (^2).map: &say
    rakudo-moar 86e7b2: OUTPUT: «0␤1␤»

But explodes if you try to both detache and use the &sub map:
    m: ^2 .map: &say
    rakudo-moar 86e7b2: OUTPUT: «===SORRY!===␤Cannot find method 'count' on 
object of type NQPMu␤»