Fix fatal error by checking if block_type asset properties are set

[noahtallen]

What?

We've noticed the following fatal error with Gutenberg 14.71, which would be great to resolve in a patch release quickly! Please merge this while I'm offline and create a path release if it looks like a reasonable approach! Or if you have a better idea, overwrite this branch or make a new PR with it! Since it's a fatal error, it'd be nice to not get blocked on async reviews ;)

[10-Dec-2022 12:41:38 UTC] PHP Fatal error:  Uncaught TypeError: array_merge(): Argument #2 must be of type array, null given in /wordpress/plugins/gutenberg/14.7.1/lib/compat/wordpress-6.2/script-loader.php:96
Stack trace:
#0 /wordpress/plugins/gutenberg/14.7.1/lib/compat/wordpress-6.2/script-loader.php(96): array_merge(Array, NULL, NULL)
#1 /wordpress/plugins/gutenberg/14.7.1/lib/compat/wordpress-6.2/script-loader.php(138): gutenberg_resolve_assets_override()
#2 /wordpress/core/6.0.3/wp-includes/class-wp-hook.php(309): {closure}(Array)
#3 /wordpress/core/6.0.3/wp-includes/plugin.php(191): WP_Hook->apply_filters(Array, Array)
#4 /wordpress/core/6.0.3/wp-includes/block-editor.php(507): apply_filters('block_editor_se...', Array, Object(WP_Block_Editor_Context))
#5 /wordpress/core/6.0.3/wp-admin/edit-form-blocks.php(282): get_block_editor_settings(Array, Object(WP_Block_Editor_Context))
#6 /wordpress/core/6.0.3/wp-admin/post.php(187): require('/wordpress/core...')
#7 {main}
  thrown in /wordpress/plugins/gutenberg/14.7.1/lib/compat/wordpress-6.2/script-loader.php on line 96

This adds some safeguards in case these values are not defined or null (isset). Since these new asset properties were introduced in 6.1, they won't work in 6.0.

Question: why is the 6.2 compat lib loaded for WordPress 6.0??

This was answered for me: 6.2 compat lib is loaded to provide compatibility with 6.2 Gutenberg features to older WordPress versions.

Why?

To fix the fatal.

How?

Check if properties isset, and use an empty array if not.

Testing Instructions

Set your .wp-env.override.json file to this to get PHP 8 and WP 6.0

{
	"core": "https://wordpress.org/wordpress-6.0.zip",
	"phpVersion": "8.0"
}

Checkout the current Gutenberg release locally: git checkout tags/v14.7.1.

If you build the Gutenberg plugin and start wp-env, the page will crash trying to edit a post. If you apply the change in this PR, you should be able to edit the post.

Testing Instructions for Keyboard

Screenshots or screencast

demo of fix:

Screen.Recording.2022-12-13.at.1.29.33.PM.mov

[youknowriad]

@noahtallen Were you able to identify the commit or PR that introduced these properties initially? We might want to ask the author to provide compatibility with 6.0 for it.

[noahtallen]

@youknowriad I think it was added in #44298, which @ellatrix worked on (and I think you collaborated on)

We may try to release a patch fix here in the meantime so that we can resolve the fatal error

[fullofcaffeine]

LGTM 👍🏻

[noahtallen]

Apologies for polluting trunk with multiple commits -- I thought that it would squash merge :/