bug #372855 getOccurrencesBetween() in calTodo.js fails on tasks without entryDate or dueDate. patch by ssitter@googlemail.com, r=jminta

calendar/base/content/calendar-multiday-view.xml

@@ -1864,12 +1864,6 @@
                     (!aNewItem.entryDate || !aNewItem.dueDate || !this.calView.mTasksInView)) {
                     return;
                 }
-                occs = aOldItem.getOccurrencesBetween(this.calView.startDate,
-                                                      this.calView.queryEndDate,
-                                                      {});
-                for each (var occ in occs) {
-                    this.calView.doDeleteEvent(occ);
-                }
 
                 occs = aNewItem.getOccurrencesBetween(this.calView.startDate,
                                                       this.calView.queryEndDate,

calendar/base/src/calUtils.js

@@ -564,6 +564,9 @@ function compareObjects(aObject, aOtherObject, aIID) {
  * @param aDate  the date or datetime to check
  */
 function ensureDateTime(aDate) {
+    if (!aDate) {
+        return null;
+    }
     if (!aDate.isDate) {
         return aDate;
     }