Resolve *-loader packages using require.resolve

packages/next-css/css-loader-config.js

@@ -76,15 +76,15 @@ module.exports = (
     )
 
     postcssLoader = {
-      loader: 'postcss-loader',
+      loader: require.resolve('postcss-loader'),
       options: Object.assign({}, postcssLoaderOptions, {
         config: postcssOptionsConfig
       })
     }
   }
 
   const cssLoader = {
-    loader: 'css-loader',
+    loader: require.resolve('css-loader'),
     options: Object.assign(
       {},
       {
@@ -99,7 +99,7 @@ module.exports = (
 
   // When not using css modules we don't transpile on the server
   if (isServer && !cssLoader.options.modules) {
-    return ['ignore-loader']
+    return [require.resolve('ignore-loader')]
   }
 
   // When on the server and using css modules we transpile the css

packages/next-less/index.js

@@ -26,7 +26,7 @@ module.exports = (nextConfig = {}) => {
         isServer,
         loaders: [
           {
-            loader: 'less-loader',
+            loader: require.resolve('less-loader'),
             options: lessLoaderOptions
           }
         ]

packages/next-sass/index.js

@@ -26,7 +26,7 @@ module.exports = (nextConfig = {}) => {
         isServer,
         loaders: [
           {
-            loader: 'sass-loader',
+            loader: require.resolve('sass-loader'),
             options: sassLoaderOptions
           }
         ]

packages/next-stylus/index.js

@@ -26,7 +26,7 @@ module.exports = (nextConfig = {}) => {
         isServer,
         loaders: [
           {
-            loader: 'stylus-loader',
+            loader: require.resolve('stylus-loader'),
             options: stylusLoaderOptions
           }
         ]

packages/next-workers/index.js

@@ -9,7 +9,7 @@ module.exports = (nextConfig = {}) => {
 
       config.module.rules.push({
         test: /\.worker\.js$/,
-        loader: 'worker-loader',
+        loader: require.resolve('worker-loader'),
         options: nextConfig.workerLoaderOptions || {
           name: 'static/[hash].worker.js',
           publicPath: '/_next/'