try to instantiate the handler before upgrading

Signed-off-by: Ludovic Orban <lorban@bitronix.be>

jetty-server/src/main/java/org/eclipse/jetty/server/Request.java

@@ -2387,11 +2387,6 @@ public <T extends HttpUpgradeHandler> T upgrade(Class<T> handlerClass) throws IO
         if (response.isCommitted())
             throw new IllegalStateException("Cannot upgrade committed response");
 
-        _channel.servletUpgrade(); // tell the channel that it is now handling an upgraded servlet
-        HttpConnection httpConnection = (HttpConnection)_channel.getConnection();
-        httpConnection.getParser().servletUpgrade(); // tell the parser it's now parsing content
-        AsyncContext asyncContext = forceStartAsync(); // force the servlet in async mode
-
         T handler;
         try
         {
@@ -2402,6 +2397,11 @@ public <T extends HttpUpgradeHandler> T upgrade(Class<T> handlerClass) throws IO
             throw new ServletException("Unable to instantiate handler class", e);
         }
 
+        _channel.servletUpgrade(); // tell the channel that it is now handling an upgraded servlet
+        HttpConnection httpConnection = (HttpConnection)_channel.getConnection();
+        httpConnection.getParser().servletUpgrade(); // tell the parser it's now parsing content
+        AsyncContext asyncContext = forceStartAsync(); // force the servlet in async mode
+
         ServletOutputStream outputStream = response.getOutputStream();
         ServletInputStream inputStream = getInputStream();
         handler.init(new WebConnection()