Fatal error: must be of type Countable

[bekopharm]

Semantic-Linkbacks 3.11.0
Wordpress 5.8.3
PHP 8.0

A Webmention didn't make it due to an Fatal Error at this line:

wordpress-semantic-linkbacks/includes/class-linkbacks-mf2-handler.php

Line 399 in 3e70f3c

if ( 1 === count( $item ) ) {

PHP Fatal error: Uncaught TypeError: count(): Argument #1 ($item) must be of type Countable|array

For unknown reasons $item was undefined.

The Webmention in question was https://php.microformats.io/?url=https%3A%2F%2Finhji.de%2Fnotes%2F1644845272

I added this little hack to wp-content/plugins/semantic-linkbacks/includes/class-linkbacks-mf2-handler.php:

        public static function flatten_microformats( $item ) {
                $flat = array();
                if(!$item) {
                        return $flat;
                }
                if ( 1 === count( $item ) ) {

And pulled it in manually via wp-json/webmention/1.0/endpoint. The Webmention is now live.

[pfefferle]

Would you like to make a PR?

[lordmatt]

Can confirm. Some static functions return null when they give up but nulls are not checked for. I used a similar hack.

[bekopharm]

Don't have a dev system set up and I'm unaware of side effects so I don't feel comfortable with a PR at this point.

[pfefferle]

No problem!

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[bekopharm]

Good thing I noted this down. Some update removed my hack again and it started failing again.