C_017_R1 Check that questions exist before loading static symptom check

I discovered this while working on #1264 (closed)/#1251 (closed):

When receiving a symptom check through a static QR code (= where the questions are hard-coded into the app), we should check that all questions actually exist before accepting the symptom check. Otherwise, the missing question is passed to the query run as undefined, causing a ton of downstream errors and heavy performance issues. This actually generated around 1,000 console outputs for me).

The user should receive an error message. Right now, nothing happens and they only see an empty query run:

My idea would be to add such a check to RccPreConfiguredSymptomCheckService, but there might be a better solution.

Symptom checks received from the HCP app (the normal way) are not affected, there the questions are sent as part of the symptom check!