Function check_capture

deps/lua/src/lstrlib.c:186–191

static int check_capture (MatchState *ms, int l) {
  l -= '1';
  if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
    return luaL_error(ms->L, "invalid capture index");
  return l;
}


static int capture_to_close (MatchState *ms) {