Mini-css-extract-plugin not found when installed, what could be the problem?

Question

webpack

installed webpack 4, started working, everything seemed to be going fine, but the moment when I started installing css-loader and style-loader (for processing css code) after entering npm run build, the app.css file is not added, after I installed the mini-css package -extract-plugin, and with npm run build an error that it will not find the module, I have been suffering for 5 hours and I can’t figure out how to fix it and what I did wrong