Error messages are displayed in legacy widgets in 5.8beta1

[piotrbak]

Description

When there's an error happening while block editor is loaded + debug log is enabled, we're displaying the error in each instance of legacy widgets.

Step-by-step reproduction instructions

1. Enable debug log, set WP_DEBUG_DISPLAY to true
2. Install Imagify and Yoast
3. Make sure there are some legacy widgets
4. Go to the Widgets section
5. See errors present in each widget section

Expected behaviour

Errors shouldn't be printed there

Actual behaviour

Errors are being repeated in each instance of widgets, they're disappearing when clicking on the widget

Screenshots or screen recording (optional)

https://jmp.sh/JzVG8SS

WordPress information

• WordPress version: 5.8-beta1-51137
• Gutenberg version: Not installed
• Are all plugins except Gutenberg deactivated? No
• Are you using a default theme (e.g. Twenty Twenty-One)? No

Device information

• Device: Desktop
• Operating system: Windows 10
• Browser: Chrome

[draganescu]

I tested this and it's as described. Just installing Imagify and Yoast (no configuration just activation) creates errors. If some plugin causes an error:

a) without WP_DEBUG

b) with WP_DEBUG

I wonder what we should do though? The errors are legit. Should the rendering endpoing :hack: the errors out of the response?

[noisysocks]

I'm surprised to see that get_current_screen is undefined. Perhaps intercepting the iframe request in init is too early. We need to intercept the request before headers are sent but after most of WordPress has loaded.

gutenberg/packages/widgets/src/blocks/legacy-widget/index.php

Line 120 in f1f0cd7

add_action( 'init', 'handle_legacy_widget_preview_iframe', 21 );

[adamziel]

admin_init perhaps? get_current_screen seems to be defined in src/wp-admin/includes/screen.php which is included in wp-admin/includes/admin.php; It seems like I need to upgrade my local setup to actually try this though as it seems to be going through core PHP files, not the ones in my Gutenberg plugin

[adamziel]

I proposed a fix in #32854