fix some glitches related to duplicating events

app/src/main/kotlin/com/simplemobiletools/calendar/pro/activities/EventActivity.kt

@@ -95,10 +95,10 @@ class EventActivity : SimpleActivity() {
             }
 
             if (intent.getBooleanExtra(IS_DUPLICATE_INTENT, false)) {
-                mEvent.id = 0
+                mEvent.id = null
+            } else {
+                cancelNotification(mEvent.id!!)
             }
-
-            cancelNotification(mEvent.id!!)
         } else {
             mEvent = Event(null)
             config.apply {

app/src/main/kotlin/com/simplemobiletools/calendar/pro/helpers/EventsHelper.kt

@@ -128,6 +128,10 @@ class EventsHelper(val context: Context) {
     fun deleteEvent(id: Long, deleteFromCalDAV: Boolean) = deleteEvents(arrayListOf(id), deleteFromCalDAV)
 
     fun deleteEvents(ids: MutableList<Long>, deleteFromCalDAV: Boolean) {
+        if (ids.isEmpty()) {
+            return
+        }
+
         val eventsWithImportId = eventsDB.getEventsByIdsWithImportIds(ids)
         eventsDB.deleteEvents(ids)