Error processing email: null

FATAL 2017-04-26T00:37:23,800 (Worker thread '0') - Error tossed: null
java.lang.NullPointerException
	at org.apache.manifoldcf.crawler.connectors.email.EmailConnector.processDocuments(EmailConnector.java:687) ~[?:?]
	at org.apache.manifoldcf.crawler.system.WorkerThread.run(WorkerThread.java:399) [classes/:?]
DEBUG 2017-04-26T00:37:24,860 (Worker thread '2') - Email: Processing document identifier 'test:<CADNgPDgBOLCnK-mobXia_Af-m4Qmc3p4Mr+k=jgy6O3-nB5C7A@mail.gmail.com>'
FATAL 2017-04-26T00:37:26,096 (Worker thread '2') - Error tossed: null
java.lang.NullPointerException
	at org.apache.manifoldcf.crawler.connectors.email.EmailConnector.processDocuments(EmailConnector.java:687) ~[?:?]
	at org.apache.manifoldcf.crawler.system.WorkerThread.run(WorkerThread.java:399) [classes/:?]
DEBUG 2017-04-26T00:37:26,887 (Worker thread '1') - Email: Processing document identifier 'test:<CADNgPDgBOLCnK-mobXia_Af-m4Qmc3p4Mr+k=jgy6O3-nB5C7A@mail.gmail.com>'
FATAL 2017-04-26T00:37:28,019 (Worker thread '1') - Error tossed: null
java.lang.NullPointerException
	at org.apache.manifoldcf.crawler.connectors.email.EmailConnector.processDocuments(EmailConnector.java:687) ~[?:?]
	at org.apache.manifoldcf.crawler.system.WorkerThread.run(WorkerThread.java:399) [classes/:?]
DEBUG 2017-04-26T00:37:28,961 (Worker thread '4') - Email: Processing document identifier 'test:<CADNgPDgBOLCnK-mobXia_Af-m4Qmc3p4Mr+k=jgy6O3-nB5C7A@mail.gmail.com>'
FATAL 2017-04-26T00:37:31,037 (Worker thread '4') - Error tossed: null