CC-3949: On edit empty show, time_filled becomes null

- fixed

airtime_mvc/application/models/airtime/CcShowInstances.php

@@ -160,8 +160,12 @@ class CcShowInstances extends BaseCcShowInstances {
      * @param PropelPDO $con A connection object
      */
     public function updateDbTimeFilled(PropelPDO $con)
-    {
-        $this->setDbTimeFilled($this->computeDbTimeFilled($con));
+    {
+        $timefilled = $this->computeDbTimeFilled($con);
+        if($timefilled == null){
+            $timefilled = "00:00:00";
+        }
+        $this->setDbTimeFilled($timefilled);
         $this->save($con);
     }