webpack 3 already deprecated this.options in the loader context. webpack 4 removes it now.
Guideline: Loaders should receive all options via this.query. They should not use other ways to receive options, i. e. no property in webpack options, no environment variable.
elmx-webpack-preloader/index.js:24:35
In webpack there is no
this.options
variablehttps://medium.com/webpack/webpack-4-migration-guide-for-plugins-loaders-20a79b927202