Webpack 4.x build error

Error:
```java
WARNING in ./node_modules/formidable/lib/file.js 1:43-50
Critical dependency: require function is used in a way in which dependencies cannot be statically extracted
@ ./node_modules/formidable/lib/incoming_form.js
@ ./node_modules/formidable/lib/index.js
@ ./node_modules/koa-body/index.js
@ ./index.js
```

Example, formidable lib:
```js
if (global.GENTLY) require = GENTLY.hijack(require);
```