Fix support for DynamicEntryPlugin (#1319)

Author: mikegreiling

lib/util/addDevServerEntrypoints.js

@@ -19,16 +19,22 @@ module.exports = function addDevServerEntrypoints(webpackOptions, devServerOptio
 
     if (devServerOptions.hotOnly) { devClient.push('webpack/hot/only-dev-server'); } else if (devServerOptions.hot) { devClient.push('webpack/hot/dev-server'); }
 
-    [].concat(webpackOptions).forEach((wpOpt) => {
-      if (typeof wpOpt.entry === 'object' && !Array.isArray(wpOpt.entry)) {
-        Object.keys(wpOpt.entry).forEach((key) => {
-          wpOpt.entry[key] = devClient.concat(wpOpt.entry[key]);
+    const prependDevClient = (entry) => {
+      if (typeof entry === 'function') {
+        return () => Promise.resolve(entry()).then(prependDevClient);
+      }
+      if (typeof entry === 'object' && !Array.isArray(entry)) {
+        const entryClone = {};
+        Object.keys(entry).forEach((key) => {
+          entryClone[key] = devClient.concat(entry[key]);
         });
-      } else if (typeof wpOpt.entry === 'function') {
-        wpOpt.entry = wpOpt.entry(devClient);
-      } else {
-        wpOpt.entry = devClient.concat(wpOpt.entry);
+        return entryClone;
       }
+      return devClient.concat(entry);
+    };
+
+    [].concat(webpackOptions).forEach((wpOpt) => {
+      wpOpt.entry = prependDevClient(wpOpt.entry);
     });
   }
 };