java.lang.NullPointerException
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.checkAddTypeUnion(StructureDefinitionComparer.java:910)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.unionTypes(StructureDefinitionComparer.java:846)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareElements(StructureDefinitionComparer.java:270)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareChildren(StructureDefinitionComparer.java:374)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareElements(StructureDefinitionComparer.java:287)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compare(StructureDefinitionComparer.java:167)
	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:100)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.checkAddTypeUnion(StructureDefinitionComparer.java:909)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.unionTypes(StructureDefinitionComparer.java:846)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareElements(StructureDefinitionComparer.java:270)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareChildren(StructureDefinitionComparer.java:374)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareElements(StructureDefinitionComparer.java:287)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compare(StructureDefinitionComparer.java:167)
	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:100)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.checkAddTypeUnion(StructureDefinitionComparer.java:909)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.unionTypes(StructureDefinitionComparer.java:846)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareElements(StructureDefinitionComparer.java:270)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareChildren(StructureDefinitionComparer.java:374)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareElements(StructureDefinitionComparer.java:287)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compare(StructureDefinitionComparer.java:167)
	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:100)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.checkAddTypeUnion(StructureDefinitionComparer.java:909)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.unionTypes(StructureDefinitionComparer.java:846)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareElements(StructureDefinitionComparer.java:270)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareChildren(StructureDefinitionComparer.java:374)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareElements(StructureDefinitionComparer.java:287)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compare(StructureDefinitionComparer.java:167)
	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:100)
	at org.hl7.fhir.igtools.publisher.comparators.PreviousVersionComparator.finishChecks(PreviousVersionComparator.java:262)
	at org.hl7.fhir.igtools.publisher.Publisher.checkConformanceResources(Publisher.java:5650)
	at org.hl7.fhir.igtools.publisher.Publisher.loadConformance(Publisher.java:5487)
	at org.hl7.fhir.igtools.publisher.Publisher.createIg(Publisher.java:1051)
	at org.hl7.fhir.igtools.publisher.Publisher.execute(Publisher.java:898)
	at org.hl7.fhir.igtools.publisher.Publisher.main(Publisher.java:11775)
	at org.hl7.fhir.igtools.web.PublicationProcess.runBuild(PublicationProcess.java:874)
	at org.hl7.fhir.igtools.web.PublicationProcess.doPublish(PublicationProcess.java:474)
	at org.hl7.fhir.igtools.web.PublicationProcess.publishInner2(PublicationProcess.java:391)
	at org.hl7.fhir.igtools.web.PublicationProcess.publishInner(PublicationProcess.java:232)
	at org.hl7.fhir.igtools.web.PublicationProcess.publish(PublicationProcess.java:125)
	at org.hl7.fhir.igtools.publisher.Publisher.main(Publisher.java:11532)