What do you mean by "debugging" and what about it do you find being difficult with Struts?
If you're talking about debugging as in "using my
IDE's debugger", then it should be no different from using, for example, plain
Java Servlets.
If you're talking about "printing out stuff so that I can figure out later what exactly happened that lead to getting HTTP 500 on the browser", again, it should be no different from any other framework.