Conditional logic to drop dummy field

In some cases, the _qvctemp.LineageInfo_qvd.DummyField is not present.
Added logic to make the drop of this field conditional to avoid script
error.

QVC_Source/Qvc_DataLineage.qvs

@@ -162,7 +162,9 @@ LET ErrorMode=$(_qvctemp.SaveErrorMode);	// Restore the ErrorMode
 
 
 // Clean up temp variables
-DROP FIELD _qvctemp.LineageInfo_qvd.DummyField;
+IF FieldValueCount('_qvctemp.LineageInfo_qvd.DummyField') > 0 THEN   // If we have a dummy field,
+	DROP FIELD _qvctemp.LineageInfo_qvd.DummyField;
+ENDIF
 SET _qvwpath=;
 SET _qvctemp.lineageRow=;
 SET _qvctemp.vCreatorDoc=;