Fix possible null dereference (Coverity 1167310)

kaevent.cpp

@@ -2970,22 +2970,18 @@ void KAEvent::setRecurrence(const KARecurrence& recurrence)
 void KAEventPrivate::setRecurrence(const KARecurrence& recurrence)
 {
     startChanges();   // prevent multiple trigger time evaluation here
-    delete mRecurrence;
     if (recurrence.recurs())
     {
+        delete mRecurrence;
         mRecurrence = new KARecurrence(recurrence);
         mRecurrence->setStartDateTime(mStartDateTime.effectiveKDateTime(), mStartDateTime.isDateOnly());
         mTriggerChanged = true;
+
+        // Adjust sub-repetition values to fit the recurrence.
+        setRepetition(mRepetition);
     }
     else
-    {
-        if (mRecurrence)
-            mTriggerChanged = true;
-        mRecurrence = 0;
-    }
-
-    // Adjust sub-repetition values to fit the recurrence.
-    setRepetition(mRepetition);
+        clearRecur();
 
     endChanges();
 }