OO-1068: fix a red screen if the extended search of question poll catch an...

OO-1068: fix a red screen if the extended search of question poll catch an event from the  controller with the table

src/main/java/org/olat/modules/qpool/ui/metadata/ExtendedSearchController.java

@@ -140,10 +140,11 @@ public class ExtendedSearchController extends FormBasicController implements Ext
 			}
 		} else if(source instanceof FormLink) {
 			FormLink button = (FormLink)source;
-			ConditionalQuery query = (ConditionalQuery)button.getUserObject();
 			if(button.getCmd().startsWith("add")) {
+				ConditionalQuery query = (ConditionalQuery)button.getUserObject();
 				addParameter(query);
 			} else if(button.getCmd().startsWith("remove")) {
+				ConditionalQuery query = (ConditionalQuery)button.getUserObject();
 				removeParameter(query);
 			}
 		}