Importing invalid XML file generates un-recoverable NPE crash

We have a user who downloaded an xml assessment file, tried to edit it (creating an invalid format – see attached), and then tried to import the file. If there is already an existing question pool, importing this invalid xml file generates first an error on import:

java.lang.RuntimeException: Invalid QTI XML format.
at org.sakaiproject.tool.assessment.qti.helper.AuthoringHelper.createImportedAssessment(AuthoringHelper.java:572)
at org.sakaiproject.tool.assessment.qti.helper.AuthoringHelper.createImportedAssessment(AuthoringHelper.java:505)
at org.sakaiproject.tool.assessment.services.qti.QTIService.createImportedAssessment(QTIService.java:107)
at org.sakaiproject.tool.assessment.ui.bean.qti.XMLImportBean.createImportedAssessment(XMLImportBean.java:405)
at org.sakaiproject.tool.assessment.ui.bean.qti.XMLImportBean.processFile(XMLImportBean.java:291)
at org.sakaiproject.tool.assessment.ui.bean.qti.XMLImportBean.importAssessment(XMLImportBean.java:174)
at org.sakaiproject.tool.assessment.ui.bean.qti.XMLImportBean.importAssessment(XMLImportBean.java:152)

But following the import, every time the user tries to access the Question Pools, they see this error:

java.lang.NullPointerException
at java.text.RuleBasedCollator.compare(RuleBasedCollator.java:351)
at org.sakaiproject.tool.assessment.ui.bean.questionpool.QuestionPoolBean$TitleComparator.compare(QuestionPoolBean.java:238)
at java.util.Arrays.mergeSort(Arrays.java:758)
at java.util.Arrays.legacyMergeSort(Arrays.java:668)
at java.util.Arrays.sort(Arrays.java:657)
at java.util.Collections.sort(Collections.java:217)
at org.sakaiproject.tool.assessment.ui.bean.questionpool.QuestionPoolBean.sortQpoolsByProperty(QuestionPoolBean.java:254)
at org.sakaiproject.tool.assessment.ui.bean.questionpool.QuestionPoolBean.sortPoolByLevel(QuestionPoolBean.java:1978)
at org.sakaiproject.tool.assessment.ui.bean.questionpool.QuestionPoolBean.setQpDataModelByLevel(QuestionPoolBean.java:2074)