Moved querying of environment variable
Moved querying of environment variable

This fixes issues when environment variable is not configured before importing the module... which can be true for I figure a lot of Webpack configuration generators/factories like [edge-builder](https://github.com/sebastian-software/edge-builder). It imports dependencies via ESM import and executes the `main` function afterwards to parse command line arguments, etc.
brightbytes/extract-css-chunks-webpack-plugin,brightbytes/extract-css-chunks-webpack-plugin,faceyspacey/extract-css-chunks-webpack-plugin,faceyspacey/extract-css-chunks-webpack-plugin