Unable to render questionnaires other than those provided in examples

[Momondoforever]

I am now trying to render questionnaires using the faiadashu example project. As stated above those questionnaires provided with the example under /assets/instruments are rendered correctly. However if I provide questionnaires from the official fhir examples from versions 4.6.0, 4.3.0 and 4.0.1 I get errors like "unable to load asset ... " or type "null" is not a subtype of type "string" in type cast. So for me it is not understandable which versions faiadashu is compatible with or what is missing. Since I am using the example project my issue is reproducible by downloading the example fhir package under: http://hl7.org/fhir/directory.html