[perl #77784] [BUG] Rakudo fails to give "Null regex not allowed" for a number of operators

[Carl Mäsak]

# New Ticket Created by  "Carl Mäsak" 
# Please include the string:  [perl #77784]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=77784 >


<moritz_> std: / /
<p6eval> std 32123: OUTPUT«===SORRY!===␤Null regex
not allowed [...] FAILED 00:01 114m␤»
<moritz_> rakudo: / /
<p6eval> rakudo ce565f: OUTPUT«===SORRY!===␤Null regex not allowed [...]
<moritz_> rakudo: / & /
<p6eval> rakudo ce565f:  ( no output )
<moritz_> bug
<moritz_> rakudo: / | /
<p6eval> rakudo ce565f:  ( no output )
<moritz_> same bug
<masak> std: / & /
<p6eval> std 32123: OUTPUT«===SORRY!===␤Null pattern
not allowed [...] FAILED 00:02 115m␤»

In the '|' case, it's OK for the left side to be empty, but there
should be an error for the right side being empty.