CSV Importer hangs when custom field is in incorrect scope

I tried to added the following CSV file:

Title,Status,AssignedTo,IssueType,Severity,Priority,OpenedDate,OpenedBy,Resolution,ClosedDate,ClosedBy
Error during multiflight search,Closed,bsiegel,Code Defect,1,1,8/4/2005 0:00,bsiegel,Not Repro,8/4/2005,bsiegel

with the following conf file:

1. written by PropertiesConfiguration
2. Mon Oct 10 13:26:18 PDT 2005
   project.key = BB
   project.lead = danblack
   project.description = blah
   project.url = blah
   existingprojectkey = CONFLUENCER
   project.name = Bob
   importsingleproject = true
   importexistingproject = false
   mapfromcsv = false
   field.OpenedDate = created
   field.Severity = customfield_10011
   field.OpenedBy = reporter
   field.Title = summary
   field.IssueType = type
   field.AssignedTo = assignee
   field.ClosedDate = customfield_10021
   field.ClosedBy = customfield_10023
   field.Priority = priority
   field.Resolution = resolution
   field.Status = status
   value.Status.Closed = 6
   value.Priority.1 = 1
   value.Resolution.Not Repro = 5
   value.IssueType.Code Defect = 1
   user.email.suffix = @exp.com
   date.import.format = MM/dd/yyyy
   date.fields = OpenedDate
   date.fields = ClosedDate
   user.extra.fields = customfield_10023

I see the following results in the stdout logs:
java.lang.NullPointerException
at com.atlassian.jira.external.ExternalUtils.addOptions(ExternalUtils.java:381)
at com.atlassian.jira.imports.importer.impl.DefaultJiraDataImporter.importIssues(DefaultJiraDataImporter.java:404)
at com.atlassian.jira.imports.importer.impl.DefaultJiraDataImporter.doImport(DefaultJiraDataImporter.java:84)
at com.atlassian.jira.imports.importer.impl.ImporterThread.run(ImporterThread.java:21)