java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because "ts" is null
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.findInSliceList(StructureDefinitionComparer.java:608)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareDiffChildren(StructureDefinitionComparer.java:556)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareDiff(StructureDefinitionComparer.java:477)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareDiffChildren(StructureDefinitionComparer.java:583)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compareDiff(StructureDefinitionComparer.java:477)
	at org.hl7.fhir.r5.comparison.StructureDefinitionComparer.compare(StructureDefinitionComparer.java:181)
	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:107)
	at org.hl7.fhir.igtools.publisher.comparators.PreviousVersionComparator.finishChecks(PreviousVersionComparator.java:266)
	at org.hl7.fhir.igtools.publisher.Publisher.checkConformanceResources(Publisher.java:6652)
	at org.hl7.fhir.igtools.publisher.Publisher.loadConformance2(Publisher.java:6435)
	at org.hl7.fhir.igtools.publisher.Publisher.createIg(Publisher.java:1171)
	at org.hl7.fhir.igtools.publisher.Publisher.execute(Publisher.java:1026)
	at org.hl7.fhir.igtools.publisher.Publisher.main(Publisher.java:15790)