locked version to 0.4.3 since this is fixed in 0.4.4 👍

Author: lfre

package.json

@@ -12,7 +12,7 @@
   },
   "devDependencies": {
     "css-loader": "^1.0.0",
-    "mini-css-extract-plugin": "^0.4.3",
+    "mini-css-extract-plugin": "0.4.3",
     "node-sass": "^4.9.3",
     "sass-loader": "^7.1.0",
     "webpack": "^4.19.1",