Wile E. Coyote, Super-genius

I spent much of the weekend trying to debug a strange Saxon XSLT bug.  There was a unit test that failed with the mysterious message:

 Variable Code has not been declared

This error message is nowhere to be found in the Saxon Javadoc, or anywhere it the Saxon source code, and according to Google nobody has ever reported it before.  Nor could I find any hint about what a "Variable Code" could be.

This morning I looked at my own code and, yes, I used an XSL variable which I called "Code" and which I neglected to declare.