Review

Parameters.getParameter() may throw CmdLineException.

Surround with try/catch.

• missing/exception handling

com/google/javascript/jscomp/CommandLineRunner.java

parseArguments(Parameters)

class CommandLineRunner.Flags.BooleanOptionHandler {
      @Override
      public int parseArguments(Parameters params) throws CmdLineException {
        String param = params.getParameter(0);
        if (param == null) {
          setter.addValue(true);
          return 0;
        } else {
          String lowerParam = param.toLowerCase();
          if (TRUES.contains(lowerParam)) {
            setter.addValue(true);
          } else if (FALSES.contains(lowerParam)) {
            setter.addValue(false);
          } else {
            setter.addValue(true);
            return 0;
          }
          return 1;
        }
      }

}