[perl #115726] sub infix:<> ( ){}; gives misleading error message about P5 diamond operator

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# New Ticket Created by  Paweł Pabian 
# Please include the string:  [perl #115726]
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# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=115726 >


Star 2012.10 behavior

bbkr_   r: sub infix:<> ( ){};
p6eval  rakudo c82d10: OUTPUT«===SORRY!===␤Unsupported use of <>;  in Perl 6 
please use lines() to read input, ('') to represent a null string or () to 
represent an empty list␤at /tmp/Jjxe80Ci_0:1␤»


STD behavior

std 04216b1: OUTPUT«[31m===[0mSORRY![31m===[0m␤Null operator is not allowed at 
/tmp/0aJaOg4T0V line 1:␤------> [32msub infix:<>[33m⏏[31m ( ){};[0m␤Other 
potential difficulties:␤  Pair with <> really means a Nil value, not null 
string; use :('') to represent the null string,␤  or…

bbkr_   should also complaint about something like "Null operator is not 
allowed " like STD, right?
*       bbkr_ reports
masak   yes, it should.