[perl #132186] [REGEX][PRECOMP] "getlex: outer index out of range" with precomped `constant` Regex

[via RT]

# New Ticket Created by  Zoffix Znet 
# Please include the string:  [perl #132186]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=132186 >


$ echo 'unit class Foo; constant $RT_RE  = rx/«  [RT]?"#"? <( <[0..9]>**{5..6}  
»/; method x ($e where $RT_RE) {say "in"}' > Foo.pm6
$ perl6 -I. -MFoo -e 'Foo.new.x: "R"'
getlex: outer index out of range
  in regex  at 
/tmp/tmp.pTHyHW456I/.precomp/0F8E2678B84A59BD14F72E830416039936204F36.1506252653.69083/20/201A6B3053CC1422D2C3670B62616221D2290929
 line 1
  in method x at /tmp/tmp.pTHyHW456I/Foo.pm6 (Foo) line 1
  in block <unit> at -e line 1

$ perl6 -v
This is Rakudo version 2017.09-84-gb02da4d built on MoarVM version 
2017.09.1-32-g9749b0f
implementing Perl 6.c.