Fix some PHP notices in Zotero_Date
Fix some PHP notices in Zotero_Date


zebulon2/dataserver,grumbelbart/zotero_dataserver_sualk,zebulon2/dataserver,grumbelbart/zotero_dataserver_sualk,grumbelbart/zotero_dataserver_sualk,zebulon2/dataserver,grumbelbart/zotero_dataserver_sualk,zebulon2/dataserver