add_argument fails to fail when provided with invalid arguments

[marvin1up]

parser.addArgument(['-o', '--out'], {
  help: 'Output file for metadata, default dist/__metadata__.js',
  defaultValue: 'dist/__metadata__.js',
  // required: true,
  useless: 11,
});

This example succeeds, even though useless is not a valid option. Even though this is pretty typical for JS libraries, its wrong here just as it is elsewhere. This particular issue is particularly problematic since the argument default has apparently been renamed to defaultValue so specifying an incorrect option default is silently ignored.

[rlidwka]

Fixed in 2.0 (now default stays default as it is in python, and unrecognized arguments are being thoroughly complained about).