RSS feeds cause fatal error with missing/invalid user

[rmccue]

• I've read and understood the contribution guidelines.
• I've searched for any related issues and avoided creating a duplicate issue.

Please give us a description of what happened

RSS (etc) feeds can cause a fatal error due to invalid typing from core.

To Reproduce

Step-by-step reproduction instructions

Expected results

Actual results

Screenshots, screen recording, code snippet

E_ERROR Uncaught TypeError: get_class(): Argument #1 ($object) must be of type object, bool given in /usr/src/app/content/plugins/wordpress-seo/src/integrations/front-end/feed-improvements.php:147
Stack trace:
#0 /usr/src/app/content/plugins/wordpress-seo/src/integrations/front-end/feed-improvements.php(107): Yoast\WP\SEO\Integrations\Front_End\Feed_Improvements->get_url_for_queried_object('https://www...')
#1 /usr/src/app/wordpress/wp-includes/class-wp-hook.php(312): Yoast\WP\SEO\Integrations\Front_End\Feed_Improvements->send_canonical_header(false)
#2 /usr/src/app/wordpress/wp-includes/class-wp-hook.php(334): WP_Hook->apply_filters('', Array)
#3 /usr/src/app/wordpress/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#4 /usr/src/app/wordpress/wp-includes/functions.php(1631): do_action('do_feed_rss2', false, 'rss2')
#5 /usr/src/app/wordpress/wp-includes/template-loader.php(48): do_feed()
#6 /usr/src/app/wordpress/wp-blog-header.php(19): require_once('/usr/src/app/wo...')
#7 /usr/src/app/index.php(21): require('/usr/src/app/wo...')
#8 {main}
  thrown

On these lines:

wordpress-seo/src/integrations/front-end/feed-improvements.php

Lines 144 to 147 in 0044dfb

	protected function get_url_for_queried_object( $url = '' ) {
	$queried_object = \get_queried_object();
	// Don't call get_class with null. This gives a warning.
	$class = ( $queried_object !== null ) ? \get_class( $queried_object ) : null;

This is caused by get_queried_object() returning false - this isn't a documented return type, but it can occur in a couple of ways. In this case, it's caused by WP_Query setting $query->queried_object to the result of get_userdata(), which can return false in various cases.

While it shouldn't return false for a valid author page, it is possible to do so based on other behaviour or plugins, which then becomes a fatal error rather than a 500 or 404. The code in Yoast handles null only, but should handle both null and false return values. (Additionally, core should really be coercing this from a false to a null so that it's typesafe, but it doesn't right now.)

Technical info

• If relevant, which editor is affected (or editors):

• Block Editor
• Gutenberg Editor
• Elementor Editor
• Classic Editor
• Other: n/a, core behaviour

• Which browser is affected (or browsers):

• Chrome
• Firefox
• Safari
• Other:

Used versions

• Device you are using:
• Operating system:
• PHP version:
• WordPress version:
• WordPress Theme:
• Yoast SEO version:
• Gutenberg plugin version:
• Elementor plugin version:
• Classic Editor plugin version:
• Relevant plugins in case of a bug:

(Filing this on behalf of a customer; cc @zsheaib)

[josevarghese]

Hi @rmccue

Thanks for using the Yoast SEO plugin and also for creating the issue. The issue you have noticed seems to be related to this one: #20436 or #20000.

If you are interested, you can also contribute to our plugin by submitting a PR.