fix: disable vue-style-loader when extractCSS

lib/builder/webpack/style-loader.js

@@ -63,13 +63,6 @@ export default ({ isServer }) => {
       }
     })
 
-    // Prepare vue-style-loader
-    // https://github.com/vuejs/vue-style-loader
-    loaders.unshift({
-      loader: 'vue-style-loader',
-      options: { sourceMap }
-    })
-
     // -- With extractCSS --
     if (this.options.build.extractCSS) {
       if (!isServer) {
@@ -83,6 +76,13 @@ export default ({ isServer }) => {
           })
         }
       }
+    } else {
+      // Prepare vue-style-loader
+      // https://github.com/vuejs/vue-style-loader
+      loaders.unshift({
+        loader: 'vue-style-loader',
+        options: { sourceMap }
+      })
     }
     return loaders
   }