`process.env.NODE_DEBUG` is unsafe to use directly for browser

[JounQin]

https://github.com/browserify/node-util/blob/master/util.js#L109

typeof process !== 'undefined' should be checked like at https://github.com/browserify/node-util/blob/master/util.js#L76

[JounQin]

close in favor of #43

[ljharb]

The solution to webpack 5 being broken is here: #43 (comment)