code: function(s) {
              const match = reParseRegexLiteral.exec(s);
              let regexDetails;
              if ( match !== null ) {
                  regexDetails = match[1];
                  if ( isBadRegex(regexDetails) ) { return; }
                  if ( match[2] ) {
                      regexDetails = [ regexDetails, match[2] ];
                  }
              } else {
                  regexDetails = s.replace(reEatBackslashes, '$1')
                                  .replace(reEscapeRegex, '\\$&');
                  regexToRawValue.set(regexDetails, s);
              }
              return regexDetails;
          }
docs: When dealing with literal text, we must first eat _some_ backslash characters.