Printing of `ZZRingElem` and `FqFieldElem` results in `Dummy error for jupyter` in IJulia

Reported by @chrisjefferson on Slack. I am busy right now at our workshop, but I'll try to look into this later if nobody beats me to it. But I want to make sure this is not forgotten.

Ideally we'd also add tests for this kind of problem, and run it systematically. Perhaps it should even be part of the conformance tests?
