    java.lang.NullPointerException
    	at org.hl7.fhir.r5.comparison.ProfileComparer.checkAddTypeUnion(ProfileComparer.java:595)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.unionTypes(ProfileComparer.java:534)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compareElements(ProfileComparer.java:226)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compareChildren(ProfileComparer.java:327)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compareElements(ProfileComparer.java:243)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compare(ProfileComparer.java:145)
    	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:92)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.checkAddTypeUnion(ProfileComparer.java:594)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.unionTypes(ProfileComparer.java:534)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compareElements(ProfileComparer.java:226)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compareChildren(ProfileComparer.java:327)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compareElements(ProfileComparer.java:243)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compare(ProfileComparer.java:145)
    	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:92)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.checkAddTypeUnion(ProfileComparer.java:594)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.unionTypes(ProfileComparer.java:534)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compareElements(ProfileComparer.java:226)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compareChildren(ProfileComparer.java:327)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compareElements(ProfileComparer.java:243)
    	at org.hl7.fhir.r5.comparison.ProfileComparer.compare(ProfileComparer.java:145)
    	at org.hl7.fhir.r5.comparison.ComparisonSession.compare(ComparisonSession.java:92)
    	at org.hl7.fhir.igtools.publisher.PreviousVersionComparator.finishChecks(PreviousVersionComparator.java:252)
    	at org.hl7.fhir.igtools.publisher.Publisher.checkConformanceResources(Publisher.java:4213)
    	at org.hl7.fhir.igtools.publisher.Publisher.loadConformance(Publisher.java:4119)
    	at org.hl7.fhir.igtools.publisher.Publisher.createIg(Publisher.java:947)
    	at org.hl7.fhir.igtools.publisher.Publisher.execute(Publisher.java:798)
    	at org.hl7.fhir.igtools.publisher.Publisher.main(Publisher.java:9079)
    	at org.hl7.fhir.igtools.publisher.utils.PublicationProcess.runBuild(PublicationProcess.java:329)
    	at org.hl7.fhir.igtools.publisher.utils.PublicationProcess.doPublish(PublicationProcess.java:226)
    	at org.hl7.fhir.igtools.publisher.utils.PublicationProcess.publishInner(PublicationProcess.java:175)
    	at org.hl7.fhir.igtools.publisher.utils.PublicationProcess.publish(PublicationProcess.java:61)
    	at org.hl7.fhir.igtools.publisher.Publisher.main(Publisher.java:8851)