fix: postpone initialize

Author: alexander-akait

lib/Server.js

@@ -40,7 +40,9 @@ class Server {
     this.webSocketHeartbeatInterval = 30000;
 
     normalizeOptions(this.compiler, this.options, this.logger);
+  }
 
+  initialize() {
     this.applyDevServerPlugin();
 
     this.webSocketServerImplementation = getSocketServerImplementation(
@@ -715,6 +717,8 @@ class Server {
       .then((foundPort) => {
         this.options.port = foundPort;
 
+        this.initialize();
+
         return this.server.listen(
           this.options.port,
           this.options.host,