java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because "ts" is null
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.findInSliceList(StructureDefinitionComparer.java:603)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareDiffChildren(StructureDefinitionComparer.java:551)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareDiff(StructureDefinitionComparer.java:472)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareDiffChildren(StructureDefinitionComparer.java:578)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareDiff(StructureDefinitionComparer.java:472)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compare(StructureDefinitionComparer.java:171)
	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:106)
	at org.hl7.fhir.igtools.publisher.comparators.PreviousVersionComparator.finishChecks(PreviousVersionComparator.java:268)
	at org.hl7.fhir.igtools.publisher.PublisherProcessor.checkConformanceResources(PublisherProcessor.java:1512)
	at org.hl7.fhir.igtools.publisher.PublisherProcessor.loadConformance2(PublisherProcessor.java:104)
	at org.hl7.fhir.igtools.publisher.Publisher.createIg(Publisher.java:397)
	at org.hl7.fhir.igtools.publisher.Publisher.execute(Publisher.java:226)
	at org.hl7.fhir.igtools.publisher.Publisher.main(Publisher.java:1601)
	at org.hl7.fhir.igtools.web.PublicationProcess.runBuild(PublicationProcess.java:1264)
	at org.hl7.fhir.igtools.web.PublicationProcess.doPublish(PublicationProcess.java:634)
	at org.hl7.fhir.igtools.web.PublicationProcess.publishInner2(PublicationProcess.java:526)
	at org.hl7.fhir.igtools.web.PublicationProcess.publishInner(PublicationProcess.java:297)
	at org.hl7.fhir.igtools.web.PublicationProcess.publish(PublicationProcess.java:152)
	at org.hl7.fhir.igtools.publisher.Publisher.main(Publisher.java:1340)