Fixed gtk error

source/ubl-settings-repomanager.c

@@ -1294,7 +1294,7 @@ void on_main_tree_selection_changed(GtkWidget *self, main_window *widgets){
             break;
         }
         if (main_config.last_selection){
-            gtk_tree_model_get_iter_from_string(GTK_TREE_MODEL(widgets->RepoFileList),&itar,main_config.last_selection);
+            if (gtk_tree_model_get_iter_from_string(GTK_TREE_MODEL(widgets->RepoFileList),&itar,main_config.last_selection))
                 gtk_tree_selection_select_iter(gtk_tree_view_get_selection(GTK_TREE_VIEW(widgets->RepoFileTree)),&itar);
         }
     }