NullPointerException during reindex

We recently restored our QA instance from production and I saw this in the logs during reindexing.

That field corresponds to Requirement Status.

2015-02-26 16:48:19,447 IssueIndexer:thread-5 WARN JSMI77 993x112x5 6u17p 10.217.5.137 /secure/admin/IndexReIndex.jspa [jira.issue.index.DefaultIssueDocumentFactory] Error indexing issue CPC-5856: Dropping 'customfield_23258'
java.lang.NullPointerException
at com.xpandit.raven.service.impl.M.a(Unknown Source)
at com.xpandit.raven.service.impl.M.apply(Unknown Source)
at com.google.common.collect.Iterators$7.computeNext(Iterators.java:649)
at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143)
at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138)
at com.google.common.collect.Lists.newArrayList(Lists.java:138)
at com.google.common.collect.Lists.newArrayList(Lists.java:119)
at com.xpandit.raven.service.impl.RequirementServiceImpl.c(Unknown Source)
at com.xpandit.raven.requirement.w.c(Unknown Source)
at com.xpandit.raven.customfield.RequirementStatusCustomField.a(Unknown Source)
at com.xpandit.raven.customfield.RequirementStatusCustomField.getValueFromIssue(Unknown Source)
at com.xpandit.raven.customfield.RequirementStatusCustomField.getValueFromIssue(Unknown Source)
at com.atlassian.jira.issue.fields.CustomFieldImpl.getValue(CustomFieldImpl.java:437)
at com.atlassian.jira.issue.index.indexers.impl.ExactTextCustomFieldIndexer.addDocumentFields(ExactTextCustomFieldIndexer.java:39)
at com.atlassian.jira.issue.index.indexers.impl.ExactTextCustomFieldIndexer.addDocumentFieldsSearchable(ExactTextCustomFieldIndexer.java:29)
at com.atlassian.jira.issue.index.indexers.impl.AbstractCustomFieldIndexer.addIndex(AbstractCustomFieldIndexer.java:46)
at com.atlassian.jira.issue.index.DefaultIssueDocumentFactory$Builder.add(DefaultIssueDocumentFactory.java:102)
at com.atlassian.jira.issue.index.DefaultIssueDocumentFactory$Builder.addAll(DefaultIssueDocumentFactory.java:91)
at com.atlassian.jira.issue.index.DefaultIssueDocumentFactory.apply(DefaultIssueDocumentFactory.java:60)
at com.atlassian.jira.issue.index.DefaultIssueDocumentFactory.apply(DefaultIssueDocumentFactory.java:37)
at com.atlassian.jira.issue.index.DefaultIssueIndexer$DefaultDocumentCreationStrategy.get(DefaultIssueIndexer.java:664)
at com.atlassian.jira.issue.index.DefaultIssueIndexer$IndexIssuesOperation.perform(DefaultIssueIndexer.java:502)
at com.atlassian.jira.issue.index.DefaultIssueIndexer$4$1.get(DefaultIssueIndexer.java:337)
at com.atlassian.jira.issue.index.DefaultIssueIndexer$4$1.get(DefaultIssueIndexer.java:333)
at com.atlassian.jira.index.SimpleIndexingStrategy.get(SimpleIndexingStrategy.java:9)