fix: gtk_widget_destroy: assertion 'GTK_IS_WIDGET (widget)' failed

main.c

@@ -189,7 +189,6 @@ static void on_convert_clicked(gpointer button, gpointer user)
 	dialog = gtk_file_chooser_dialog_new("Save TeX File", GTK_WINDOW(data->main_window), GTK_FILE_CHOOSER_ACTION_SAVE,
 					     "Cancel", GTK_RESPONSE_CANCEL, "Save", GTK_RESPONSE_ACCEPT, NULL);
 	res = gtk_dialog_run(GTK_DIALOG(dialog));
-	gtk_widget_destroy(dialog);
 	if (res == GTK_RESPONSE_ACCEPT) {
 		file_name = gtk_file_chooser_get_filename(GTK_FILE_CHOOSER(dialog));
 		tex_file = fopen(file_name, "w");
@@ -197,6 +196,8 @@ static void on_convert_clicked(gpointer button, gpointer user)
 		gtk_widget_destroy(dialog);
 		render_cell_to_code(cell_to_render, layer_list, tex_file);
 		fclose(tex_file);
+	} else {
+		gtk_widget_destroy(dialog);
 	}
 
 	g_list_free_full(layer_list, (GDestroyNotify)delete_layer_info_struct);