java.lang.NullPointerException
	at org.hl7.fhir.r5.comparison.CodeSystemComparer.findRightProp(CodeSystemComparer.java:321)
	at org.hl7.fhir.r5.comparison.CodeSystemComparer.mergeProps(CodeSystemComparer.java:292)
	at org.hl7.fhir.r5.comparison.CodeSystemComparer.merge(CodeSystemComparer.java:221)
	at org.hl7.fhir.r5.comparison.CodeSystemComparer.compareConcepts(CodeSystemComparer.java:166)
	at org.hl7.fhir.r5.comparison.CodeSystemComparer.compare(CodeSystemComparer.java:124)
	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:82)
	at org.hl7.fhir.igtools.publisher.PreviousVersionComparator.finishChecks(PreviousVersionComparator.java:252)
	at org.hl7.fhir.igtools.publisher.Publisher.checkConformanceResources(Publisher.java:4009)
	at org.hl7.fhir.igtools.publisher.Publisher.loadConformance(Publisher.java:3915)
	at org.hl7.fhir.igtools.publisher.Publisher.createIg(Publisher.java:890)
	at org.hl7.fhir.igtools.publisher.Publisher.execute(Publisher.java:745)
	at org.hl7.fhir.igtools.publisher.Publisher.main(Publisher.java:8561)