Error in register_block_style when should_load_separate_core_block_assets is turned on.

[shimon246]

Description

I get an error with register_block_style when I turn on should_load_separate_core_block_assets.
(= add_filter( 'should_load_separate_core_block_assets', '__return_true' ); )

Code

// Register Style.
wp_register_style(
	'core/heading',
	plugin_dir_url( __FILE__ ) . 'build/core/heading/style.css',
	array()
);

register_block_style(
	'core/heading',
	array(
		'name'       => 'heading-default',
		'label'      => 'Default',
		'style_handle' => 'core/heading',
		'is_default' => true,
	)
);

Error message

Fatal error: Uncaught ArgumentCountError: Too few arguments to function {closure}(), 1 passed in /var/www/html/wp-includes/class-wp-hook.php on line 305 and exactly 2 expected in /var/www/html/wp-includes/script-loader.php:2447 Stack trace: #0 /var/www/html/wp-includes/class-wp-hook.php(305): {closure}('\n

The relevant code

class-wp-hook.php 305
https://github.com/WordPress/wordpress-develop/blob/master/src/wp-includes/class-wp-hook.php#L305

script-loader.php 2451
https://github.com/WordPress/wordpress-develop/blob/master/src/wp-includes/script-loader.php#L2451-L2453

Expected behavior

If heading-default is set, the CSS (style.css) will be loaded, and if heading-default is not set, the CSS will not be loaded.

Related references

https://make.wordpress.org/core/2021/07/01/block-styles-loading-enhancements-in-wordpress-5-8/#comment-41478
https://core.trac.wordpress.org/ticket/53616
WordPress/wordpress-develop#1482
register_block_type is working fine.
Is register_block_style still being worked on?
If so, please let me know.

Step-by-step reproduction instructions

1.add_filter( 'should_load_separate_core_block_assets', '__return_true' ); for custom plugins etc.
2.Prepare the CSS build/core/heading/style.css
3.Paste the code to add the style for the heading block

// Register Style.
wp_register_style(
	'core/heading',
	plugin_dir_url( __FILE__ ) . 'build/core/heading/style.css',
	array()
);

register_block_style(
	'core/heading',
	array(
		'name'       => 'heading-default',
		'label'      => 'Default',
		'style_handle' => 'core/heading',
		'is_default' => true,
	)
);

[gziolo]

@aristath, I believe that wp_enqueue_block_style from #32510 tries to simplify the code shared in the example to reproduce the issue. Anyway, do you think it's something related to how should_load_separate_core_block_assets works?

[aristath]

@aristath, I believe that wp_enqueue_block_style from #32510 tries to simplify the code shared in the example to reproduce the issue.

Hmmm wp_enqueue_block_style refers to stylesheets while register_block_style is for the block-styles API, so I don't think these 2 are related 🤔

Anyway, do you think it's something related to how should_load_separate_core_block_assets works?

It could be... But using the code posted above I was unable to replicate an issue and therefore couldn't debug it.
I don't get any errors on my localhost with that code... Is the snippet perhaps missing something? Is that code added in an action/hook somewhere? wp_register_style normally goes inside a wp_enqueue_scripts action (I tried that too btw, I still didn't get any errors)

[shimon246]

@gziolo @aristath

Thanks for the comment.

Hmmm. The theme happens with Twenty Twenty-One.
TT1 and other block-based themes don't have the error, but they also don't have split loading 😣

I've never heard of the wp_enqueue_block_style function before.

It means that when I use should_load_separate_core_block_assets to load blocks separately, I should use wp_enqueue_block_style to load only when I use CSS with core styles added by register_block_style. style?

postscript:

If the style_handle of register_block_style is set to a handle name, an error is output.
If you use inline_style, no error will be printed.

[aristath]

For enqueueing stylesheets specific to a single block, you can use the code from this post: https://make.wordpress.org/core/2021/07/01/block-styles-loading-enhancements-in-wordpress-5-8/
The wp_enqueue_block_style is new and will be available in WP5.9, so if you want to be compatible with older versions on WP I wouldn't recommend using it.

Since I'm not getting an error with the code you posted, a semi-random idea: Did you try naming your stylesheet something that does not conflict with block-names? So instead of core/heading, try naming your stylesheet's handle something like my-theme-block-styles-core-heading

[shimon246]

@aristath
Thank you.🥺
I'm still getting the following error message when using style_handle

Fatal error: Uncaught ArgumentCountError: Too few arguments to function {closure}(), 1 passed in /Users/〇〇/Local Sites/〇〇/app/public/wp-includes/class-wp-hook.php on line 305 and exactly 2 expected in /Users/〇〇/Local Sites/〇〇/app/public/wp-includes/script-loader.php on line 2447

ArgumentCountError: Too few arguments to function {closure}(), 1 passed in /Users/〇〇/Local Sites/〇〇/app/public/wp-includes/class-wp-hook.php on line 305 and exactly 2 expected in /Users/〇〇/Local Sites/〇〇/app/public/wp-includes/script-loader.php on line 2447

Here is the complete code

<?php
/**
 * Plugin Name: My Plugin
 */
add_filter('should_load_separate_core_block_assets', '__return_true');

wp_register_style(
  'my-theme-block-styles-core-heading',
  plugin_dir_url(__FILE__) . 'style.css',
  array()
);

register_block_style(
  'core/heading',
  array(
    'name'         => 'my-theme-block-styles-core-heading-add',
    'label'        => 'Add',
    'style_handle' => 'my-theme-block-styles-core-heading',
    // 'inline_style' => '.wp-block-heading.is-style-heading-add , .is-style-heading-add { color: blue; }',
    )
);

Of course, this error message will only be displayed on pages that use the heading block.

[aristath]

I tried the code posted above:

• Created a new PHP file in wp-content/plugins and pasted your code
• Activated the plugin from the dashboard.

As soon as I activate the plugin, I'm getting the following error:

Notice: wp_register_style was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. This notice was triggered by the my-theme-block-styles-core-heading handle. Please see Debugging in WordPress for more information. (This message was added in version 3.3.0.) in /var/www/src/wp-includes/functions.php on line 5714

After fixing that, I can replicate the issue. I've already found the solution to it, so I'll create a new ticket in WP-Core and push a patch for it 👍

The code I used to replicate:

<?php
/**
 * Plugin Name: My Plugin
 */

add_filter( 'should_load_separate_core_block_assets', '__return_true' );
add_action( 'wp_enqueue_scripts', 'test_registering_a_block_style' );
add_action( 'admin_enqueue_scripts', 'test_registering_a_block_style' );

function test_registering_a_block_style() {
	wp_register_style(
		'my-theme-block-styles-core-heading',
		plugins_url( 'style.css', __FILE__ ),
	);
}

register_block_style(
	'core/heading',
	array(
		'name'         => 'my-theme-block-styles-core-heading-add',
		'label'        => 'Add',
		'style_handle' => 'my-theme-block-styles-core-heading',
		// 'inline_style' => '.wp-block-heading.is-style-heading-add , .is-style-heading-add { color: blue; }',
	)
);

Thank you for sticking with it and providing the necessary information to debug it! ❤️

[aristath]

Error reported in https://core.trac.wordpress.org/ticket/54323 and patch submitted.
Most likely the fix will be included in WP 5.9 👍

[skorasaurus]

@aristath thanks for the prompt fix; can we close this ticket then?

@shimon246
Thank you for the detailed feedback and reports. Please reopen if you're still experiencing this in WordPress 5.9.

[david-binda]

Sorry for commenting on an already closed issue, but I believe that it might be actually helpful, if Gutenberg could patch the issue now originating in WordPress, since in v11.8.0, it enforces the add_filter( 'should_load_separate_core_block_assets', '__return_true' ); via 5.9 compat, and thus eventually makes the fatal errors to happen in themes, which were otherwise working fine, till the v11.8.0 version.

One such an example is the blockbase theme, which in it's latest version removes the block template for 404 page, and hits the bug (if run on WordPress 5.8 with Gutenberg 11.8.0).

I have kindly opened a PR with proposed fix for Gutenberg.