PHP notice in the site editor

[carolinan]

Describe the bug
With 8.2.0 and later, this notice is showing in the site editor
Notice: Undefined index: front-page in /var/www/html/wp-content/plugins/gutenberg/lib/edit-site-page.php on line 162

https://github.com/WordPress/gutenberg/blob/master/lib/edit-site-page.php#L162

To reproduce
Steps to reproduce the behavior:

1. Install Gutenberg
2. Enable full site editing
3. Enable a theme that has support for full site editing.
   https://github.com/WordPress/theme-experiments
4. Open the site editor.
5. See PHP notice

Expected behavior
I expect experimental features to change often, but not be broken in the plugin releases. :)

Editor version (please complete the following information):
WordPress version: 5.4.1
Gutenberg: 8.2.0, 8.2.1

PHP version: 7.3.13

Desktop (please complete the following information):
Windows 10
Chrome version: 83.0.4103.61

[youknowriad]

Maybe related to this https://github.com/WordPress/gutenberg/pull/21980/files#r435217075

cc @epiqueras @noahtallen @ockham

[epiqueras]

You need to have at least an index.html block template to fall back to for this to work.

[ockham]

My bad! I'll work on a fix tomorrow.

[carolinan]

Requiring and index.html makes sense considering the template hierarchy, but the notice shows when front-page.html is missing, not when index.html is missing.

[ockham]

To repro this:

• There shouldn't be any wp_template CPTs (neither published nor auto-drafts) from previous Site Editor runs. (It's best to start with a fresh install.)
• Furthermore, the "Full Site Editing Demo Templates" checkbox in /wp-admin/admin.php?page=gutenberg-experiments must not be ticked.

[epiqueras]

but the notice shows when front-page.html is missing, not when index.html is missing.

Yes, there is a bug there.

Furthermore, the "Full Site Editing Demo Templates" checkbox in /wp-admin/admin.php?page=gutenberg-experiments must not be ticked.

Doesn't that mean there isn't an index.html template? Or are you using a theme that provides one? If that's the case, then the error is in how theme provided files are being looked up. It should be easy to debug that.

[ockham]

but the notice shows when front-page.html is missing, not when index.html is missing.

Yes, there is a bug there.

Right, this is one part of the problem. I think I'm setting the wrong key here:

gutenberg/lib/edit-site-page.php

Line 158 in 710373b

$template_ids[ $current_template['template_post']->post_name ] = $current_template['template_post']->ID;

This will use the name of the template that was found, not the name of the key that was looked for. So if we're looking up front-page, but don't find any template, and thus fall back to index, the template will be stored under the index key, rather than the front-end one.

I think the fix for this is to use the template we were looking for as key:

diff --git a/lib/edit-site-page.php b/lib/edit-site-page.php
index 817c3ef9cb..0dcaf92d6a 100644
--- a/lib/edit-site-page.php
+++ b/lib/edit-site-page.php
@@ -155,7 +155,7 @@ function gutenberg_edit_site_init( $hook ) {
 
                $current_template = gutenberg_find_template_post_and_parts( $template_type );
                if ( isset( $current_template ) ) {
-                       $template_ids[ $current_template['template_post']->post_name ] = $current_template['template_post']->ID;
+                       $template_ids[ $template_type ] = $current_template['template_post']->ID;
                        $template_part_ids = $template_part_ids + $current_template['template_part_ids'];
                }
        }

This should make the error go away when there's no front-page.html, but an index.html -- e.g. for Twenty Twenty Blocks 🤞

Furthermore, the "Full Site Editing Demo Templates" checkbox in /wp-admin/admin.php?page=gutenberg-experiments must not be ticked.

Doesn't that mean there isn't an index.html template? Or are you using a theme that provides one? If that's the case, then the error is in how theme provided files are being looked up. It should be easy to debug that.

The theme I was testing this with was Twenty Twenty (i.e. not the 'Blocks' version), so no index.html. I'm still getting the error about the missing front-page index with themes that don't come with block template, this will need separate fixing. I left a related note here.

[epiqueras]

That fix makes sense. Let's ship it.

[ockham]

That fix makes sense. Let's ship it.

Working on a PR that also addresses this problem.