Fix filesystem path loading

Author: xpdota

packages/beasties-webpack-plugin/src/index.js

@@ -175,7 +175,7 @@ export default class BeastiesWebpackPlugin extends Beasties {
 
     if (!sheet) {
       try {
-        sheet = await this.readFile(this.compilation, filename)
+        sheet = await this.readFile(filename)
         this.logger.warn(
           `Stylesheet "${relativePath}" not found in assets, but a file was located on disk.${
             this.options.pruneSource