Ajax PHP warning

I’m using the plugin “query monitor” and this is its output to the JS console:

=== PHP Error in AJAX Response === query-monitor.js:198:5
Object {
   type: "notice"
   message: "Undefined index: show_excerpt"
   file: "\wp-content\plugins\feature-a-page-widget\inc\fpw_widget_class.php"
   line: 224
   stack: Array[4]
      0: FPW_Widget->update()
      1: WP_Widget->update_callback()
      2: wp_ajax_save_widget()
      3: do_action('wp_ajax_save-widget')
}

Lines 222 – 224 just need some isset() checks, I think:

$instance['show_title'] = (bool) $new_instance['show_title'];
$instance['show_image'] = (bool) $new_instance['show_image'];
$instance['show_excerpt'] = (bool) $new_instance['show_excerpt'];
$instance['show_read_more'] = (bool) $new_instance['show_read_more'];

I get a warning per unchecked option when saving the widget in admin->appearance->widgets.