That's also confusing me, and forgive me if I don't have tags figured out yet, the assignStep0.tag file is 257 lines long. (below) I'm not sure if it's expanding somewhere, or if I have the wrong place.
One of the many many reasons that scriptlets in JSPs have been discredited for 10 years now (they were replaced with the JSTL and EL with JSP2 in 2002!) is the difficulty in diagnosing problems such as this.
When modern JSPs contain only JSTL and EL, it's almost impossible for these types of errors to occur.
My advice at this point can only be to update your JSP knowledge with JSTL and EL and move all that Java code out of your JSPs and tags.
You might want to read this article for information on structuring modern web apps.
Can you find anything by looking at the JSP source file directly under the tomcat work directory? I don't know how and where your tomcat is set up, but to give you an idea: