Number parsing bug

start_webpack.sh

#!/bin/bash

~> webpack --env.numerical 5 --env.commitId 12180e3
# outputs { numerical: 5, commitId: 12180000 }

~> webpack --env.numerical 5 --env.commitId "12180e3"                                                                                                                                                                                                                [255]
# outputs { numerical: 5, commitId: 12180000 }

~> webpack --env.numerical 5 --env.commitId "12180e3" --env.TEST_STRING test                                                                                                                                                                                         [255]
# { numerical: 5, commitId: 12180000, TEST_STRING: 'test' }

webpack.config.js

const util = require('util');
module.exports = (env) => console.log(util.inspect(env, { colors: true, showHidden: true }));