TypeError: Cannot read property 'javascript' of undefined + terser webpack plugin + react js

Hi you are using Webpack 4 and Terser ^5.0.0. This version of Terser is for Webpack 5, you need to set version "terser-webpack-plugin": "^4.2.3", in package.json file

You are using Webpack 4 and Terser ^5.0.0. This version of Terser is for Webpack 5, you need to set version "terser-webpack-plugin": "^4.2.3" in the package.json file.