PHP Noticed caused by Customizer if widgets panel removed

[DJPaul]

If $wp_customize->remove_panel( 'widgets' ); is done, the Customizer throws a PHP Notice:

PHP Notice: Trying to get property of non-object in /srv/www/buddypress.dev/src/wp-includes/class-wp-customize-widgets.php on line 716

Tested on 4.4 SVN branch.

[ericlewis]

Hi @DJPaul — there's a special way to remove a Customizer component.

Perhaps we need to review documentation here, to point developers in the right direction?

[DJPaul]

Thanks. I discovered the remove_panel method from a blog post on make/core. Maybe the docblock for remove_panel could say don't use this to remove the core widgets or nav menus panels, maybe.

[voldemortensen]

35242.diff adds a _doing_it_wrong warning. Thoughts?

[westonruter]

Replying to voldemortensen:

35242.diff adds a _doing_it_wrong warning. Thoughts?

Good idea.

Feedback:

• 'WP_Customize_Manager::remove_panel' can be replaced with __METHOD__.
• Version can be '4.4' since that is when the filter was introduced.
• The filter is actually customize_loaded_components.
• The link references an older proposal. I just commented with the necessary code snippets: https://core.trac.wordpress.org/ticket/33552#comment:12 Or also the Make Core post can be referenced: ​https://make.wordpress.org/core/2015/12/02/customizer-improvements-in-4-4/

[voldemortensen]

Thanks for the feedback, updated the patch.

[westonruter]

In 36216:

Customizer: Call _doing_it_wrong() if widgets or nav_menus are manually removed via WP_Customize_Manager::remove_panel().

Advise that the customize_loaded_components filter should be used instead.

Props voldemortensen.
See #33552.
Fixes #35242.

[DrewAPicture]

Following [36216]:

• Instead of arbitrarily linking a Trac comment, let's link to the code reference page for the hook where I have conveniently added simplified versions of the examples from comment:12:ticket:33552 :-)
• <code>customize_loaded_components</code> shouldn't be translatable
• The string is missing a translator comment for the specifiers

All of the above are done in 35242.2.diff​.

[westonruter]

In 36219:

Customizer: Improve _doing_it_wrong() message when widgets or nav_menus are manually removed via WP_Customize_Manager::remove_panel().

• Link to code reference page for customize_loaded_components instead of linking to a Trac comment.
• Remove HTML code from being included in translated string.
• Add missing translator comment for the specifiers in the translated string.

Amends [36216].
Props DrewAPicture.
Fixes #35242.

[westonruter]

In 36262:

Customizer: Re-use list of components to eliminate code duplication.

Introduces protected WP_Customize_Manager::$components to store list of loaded core components filtered by customize_loaded_components.

Props DrewAPicture.
See #35242
See #33552.
Fixes #35354.