Better error reporting for invalid Questionnaires

[vadi2]

In case the user has messed up their Questionnaire (say, by building it manually outside of lforms) and tries to load it into the app, scenarios like missing linkId's for enableWhen will cause JS errors which prevent rendering. It would be nice if such errors were reported back to the user so non-technical users are able to diagnose their problems better.

[plynchnlm]

I agree. We have started work on showing error messages on individual fields, but had to put it on hold. In the meantime, I would suggest posting a Questionnaire to a validating FHIR server to check for errors when the Questionnaire is still in development.