Missing resource error response when resource isn't needed

[alexisc0le]

Describe the bug
When I populate a Questionnaire on Postman with a test patient that does not have a resource associated with a CQL Statement I get the following response - "Error encountered evaluating expression (Allergies) for item (patient-info|drug-allergies): Cannot invoke "java.util.List.stream()" because the return value of "org.opencds.cqf.fhir.cql.LibraryEngine.resolveExpression(String, org.opencds.cqf.fhir.cql.CqfExpression, org.hl7.fhir.instance.model.api.IBaseParameters, org.hl7.fhir.instance.model.api.IBaseBundle)" is null".

To Reproduce
(I have been having the issue on this branch- https://github.com/cqframework/cqf-us/tree/2024-Updates-Debugging)

1. Post the MBODAQuestionnaire Bundle to Postman (/cqf-us/bundles/questionnaire/MBODAQuestionnaire/MBODAQuestionnaire-bundle.json)
2. Post USCorePatient-2 Bundle to Postman
3. Populate the Questionnaire with USCorePatient-2 (GET {{server}}/Questionnaire/MBODAQuestionnaire/$populate?subject=USCorePatient-2)
4. OPTIONAL/TO COMPARE: Post USCorePatient-1 bundle to Postman and populate the Questionnaire with USCorePatient-1

Expected Behaviour
It is expected that we don’t get that error message, and that question just be skipped/left empty.