reproduce the bug

package.json

@@ -10,7 +10,10 @@
     "build": "node build/build.js"
   },
   "dependencies": {
-    "vue": "^2.5.2"
+    "node-sass": "^4.7.2",
+    "sass-loader": "^6.0.6",
+    "vue": "^2.5.2",
+    "worker-loader": "^1.1.0"
   },
   "devDependencies": {
     "autoprefixer": "^7.1.2",

src/App.vue

@@ -7,9 +7,19 @@
 
 <script>
 import HelloWorld from './components/HelloWorld'
+import { SOME_CONSTANT } from './assets/test.scss'
+import TestWorker from 'worker-loader!./assets/test.worker.js'
 
 export default {
   name: 'App',
+  mounted () {
+    console.log('The value of the constant is', SOME_CONSTANT)
+  },
+  data () {
+    return {
+      worker: new TestWorker()
+    }
+  },
   components: {
     HelloWorld
   }

src/assets/test.scss

@@ -0,0 +1,6 @@
+$SOME_CONSTANT: 1px;
+
+:export {
+  SOME_CONSTANT: $SOME_CONSTANT;
+}
+

src/assets/test.worker.js

@@ -0,0 +1,4 @@
+import { SOME_CONSTANT } from './test.scss'
+
+console.log('This is a webworker! I\'ll do calculation with the constants defined in styles.')
+