[perl #125513] [BUG] Bogus error when putting the named slurpy *%_ before the positional slurpy *@_ in Rakudo

[Carl Mäsak]

# New Ticket Created by  "Carl Mäsak" 
# Please include the string:  [perl #125513]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=125513 >


<masak> m: class C { method foo(*%_, *@_) { say "OH HAI" } }; C.new.foo
<camelia> rakudo-moar 7b5256: OUTPUT«===SORRY!===␤Lexical '%_' already
declared␤»
* masak submits rakudobug
<masak> S06:1105: sub duplicate($n, *%flag, *@data) {...}
<masak> so it's allowed.

The source code in World.nqp assumes that the named slurpy is in
@params[+@params - 1], which isn't necessarily the case, as the spec
allows named slurpies and positional slurpies to appear in any order.