Block Editor crashes on custom post types without title support

[markjaquith]

Create a custom post type that supports 'editor' but not 'title'. Save Draft. Reload the page. Crashes.

<?php
add_action( 'init', function () {
        register_post_type( 'movie',
                [
                        'labels' => [
                                        'name' => 'Movies',
                                        'singular_name' => 'Movie',
                        ],
                        'public' => true,
                        'has_archive' => true,
                        'rewrite' => [
                                'slug' => 'movies'
                        ],
                        'show_in_rest' => true,
                        'supports' => [
                                //'title',
                                'editor',
                        ],
                ]
        );
});

[splitti]

The problem is caused by ​this line in PostLink.

It assumes that cleanForSlug (​see here) can deal with parameters that aren't strings. If this were a documentary, the narrator would now say "It can't."

There are at least two options on how to resolve this problem.

1. Make cleanForSlug bail whenever it gets invalid input.
2. Change the code in PostLink (and potentially elsewhere) to not call cleanForSlug with something that isn't always a string.

Following the ​Robustness Principle, I opted for (1) in my patch.
I'm not sure what's the best way to indicate that the function wasn't able to perform the desired action, but I think returning undefined is probably a good start, but I'd like to hear your opinions on that as well as any preference for another option :)

[splitti]

Patches cleanForSlug to not fail when the parameter isn't a string.

[splitti]

Updated patch that follows the coding standards

[splitti]

Adjusted the patch to follow the coding standards :)

[SergeyBiryukov]

The patch has been merged in ​https://github.com/WordPress/gutenberg/pull/16236 and should be included in core the next time Gutenberg packages are merged.

[JeffPaul]

Reopening this so it can be back-ported to the 5.2 branch, also needs testing to validate if this ticket is good to land in 5.2.3.

[audrasjb]

@JeffPaul Looks like it was fixed in Gutenberg so I guess there is nothing to backport here.
​https://github.com/WordPress/gutenberg/pull/16236/files/cd82bed57c1f3722460d93438148b0edd92e3892

Asking in #core-editor for confirmation :)

[audrasjb]

I asked in #core-editor and the answer was clear:

While I agree it would be good to fix the process to update the packages in Core is still not that straightforward. So given that we'll be focusing on WordPress 5.3 a lot in the next weeks and the timeline for the feature-freeze being in a month or so. I'd prefer if we just land this in WordPress 5.3 due to that overheard.

Unfortunately, the Gutenberg patch (already merged) is not going to land in 5.2.3 but it the issue will definitely be fixed in 5.3.

By the way, I'm going to close the ticket as reported-upstream since it's already fixed in Gutenberg.