Add test for REPL handling incomplete regex
Add test for REPL handling incomplete regex

As described in https://github.com/Raku/old-issue-tracker/issues/3254
the following evaluation used to fail badly in the REPL (on the JVM
backend) a couple of years ago:

  'asa' ~~ /:s ^a* %
  java.lang.NullPointerException
  java.lang.NullPointerException
  [...]
  Exception in thread "main" org.perl6.nqp.runtime.UnwindException
  [...]

The problem has been fixed a long time ago (the exact commit is
unknown) and the incomplete regex results in a sane error message,
but we didn't have a regression test, yet.

salortiz/rakudo,tbrowder/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,rakudo/rakudo,salortiz/rakudo,labster/rakudo,labster/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,labster/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,tony-o/rakudo,MasterDuke17/rakudo,rakudo/rakudo,tony-o/rakudo,salortiz/rakudo,rakudo/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,tony-o/rakudo,labster/rakudo,labster/rakudo,labster/rakudo,rakudo/rakudo,salortiz/rakudo,tony-o/rakudo,rakudo/rakudo,rakudo/rakudo,salortiz/rakudo,tony-o/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tony-o/rakudo,tbrowder/rakudo