[wp-trac] [WordPress Trac] #58183: PHP notice when accessing Customizer with a classic theme without widgets

[WordPress Trac]

#58183: PHP notice when accessing Customizer with a classic theme without widgets
--------------------------+------------------------------
 Reporter:  kraftner      |       Owner:  (none)
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  Awaiting Review
Component:  Customize     |     Version:
 Severity:  normal        |  Resolution:
 Keywords:                |     Focuses:
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Comment (by westonruter):

 Looking at this briefly, I can see that the Widgets panel is being
 [https://github.com/WordPress/wordpress-
 develop/blob/26e3948fca904db17a588d3736b3db59f8007daa/src/wp-includes
 /class-wp-customize-widgets.php#L415-L426 registered] with an
 `active_callback` set to `WP_Customize_Widgets::is_panel_active()`, which
 is [https://github.com/WordPress/wordpress-
 develop/blob/26e3948fca904db17a588d3736b3db59f8007daa/src/wp-includes
 /class-wp-customize-widgets.php#L549-L562 defined] as:

 {{{#!php
 <?php
         public function is_panel_active() {
                 global $wp_registered_sidebars;
                 return ! empty( $wp_registered_sidebars );
         }
 }}}


 This is different to how the Menus panel was being registered
 conditionally, in that instead of an `active` callback the
 `WP_Customize_Nav_Menus::check_capabilities()` method was utilized prior
 to [54419]. When `check_capabilities` is used, it will actually cause the
 panel to be [https://github.com/WordPress/wordpress-
 develop/blob/26e3948fca904db17a588d3736b3db59f8007daa/src/wp-includes
 /class-wp-customize-manager.php#L4488-L4516 removed entirely] in
 `WP_Customize_Manager::prepare_controls()` runs. This is why, as I recall,
 the notice was happening for menus, because the Panel got removed.

 I remain unsure why this is happening for Widgets since
 `check_capbilities` is not being used, but rather the `active_callback`.
 So the panel shouldn't be getting removed.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/58183#comment:2>
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