If you include the
file in your Modules directory
at a path of 'optional-library/xqrs-error.xsl' relative to
xqrs.xqy, then XQRS will make use of this to show you errors,
stack traces and code snippets in greater detail which may help
you in debugging your code and during development.
The following is a screen shot of the kind of view it
gives for errors when they occur.