Fatal error due to admin bar disabled

[amarinediary]

Bug Description

Hiding the Wordpress admin bar via the show_admin_bar hook filter will result in a fatal error. on the AMP Validated URL screen on Recheck user action.

Fatal error: Uncaught DivisionByZeroError:
Division by zero in C:\xampp\htdocs\www\wordpress\wp-content\plugins\amp\includes\validation\class-amp-validated-url-post-type.php:2542 Stack trace: #0 C:\xampp\htdocs\www\wordpress\wp-admin\includes\template.php(1389):
AMP_Validated_URL_Post_Type::print_stylesheets_meta_box(Object(WP_Post), Array)

1. C:\xampp\htdocs\www\wordpress\wp-admin\edit-form-advanced.php(688): do_meta_boxes(Object(WP_Screen), 'normal', Object(WP_Post))
2. C:\xampp\htdocs\www\wordpress\wp-admin\post.php(206): require('C:\xampp\htdocs...')
3. {main} thrown in C:\xampp\htdocs\www\wordpress\wp-content\plugins\amp\includes\validation\class-amp-validated-url-post-type.php on line 2542
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Expected Behaviour

Using recheck shouldn't return a fatal error when the admin bar isn't displayed;

Steps to reproduce

1. Go to function.php
2. Add the following function:

<?php

add_filter( 'show_admin_bar', function() {
    if ( ! is_admin() )
        return false;
} );

3 .Go to the AMP Validated URL page and click Recheck
4. See error

Screenshots

Additional context

• WordPress version: 5.7.1
• Plugin version: 2.1.1
• Gutenberg plugin version (if applicable): Not applicable
• AMP plugin template mode: Standard
• PHP version: 8.0
• OS: Windows
• Browser: Chrome
• Device: PC

Additional information

All plugins disabled. Fresh WordPress install and blank theme. Site health passed.

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Acceptance criteria

Implementation brief

QA testing instructions

Demo

Changelog entry

[westonruter]

I'm not able to reproduce the error due to the the admin bar being hidden. Nevertheless, your PHP code to hide the admin bar should be modified as follows:

add_filter( 'show_admin_bar', function( $show ) {
	if ( ! is_admin() ) {
		$show = false;
	}
	return $show;
} );

The error seems unrelated to the admin bar being shown. At issue is this code here:

amp-wp/includes/validation/class-amp-validated-url-post-type.php

Line 2542 in be84e8a

$percentage = $stylesheet['final_size'] / ( $included_final_size + $excluded_final_size );

Apparently for you one stylesheet has a $included_final_size and $excluded_final_size which both add up to zero, which is surprising. As a quick fix to assist with debugging and to prevent the fatal error you can try this patch:

diff --git a/includes/validation/class-amp-validated-url-post-type.php b/includes/validation/class-amp-validated-url-post-type.php
index 2e0ad95e2..f51332c6c 100644
--- a/includes/validation/class-amp-validated-url-post-type.php
+++ b/includes/validation/class-amp-validated-url-post-type.php
@@ -2539,11 +2539,16 @@ static function ( $a, $b ) use ( $stylesheets ) {
 					</td>
 					<td class="column-percentage">
 						<?php
-						$percentage = $stylesheet['final_size'] / ( $included_final_size + $excluded_final_size );
+						$denominator = ( $included_final_size + $excluded_final_size );
 						?>
-						<meter value="<?php echo esc_attr( $stylesheet['final_size'] ); ?>" min="0" max="<?php echo esc_attr( $included_final_size + $excluded_final_size ); ?>" title="<?php esc_attr_e( 'Stylesheet bytes of total CSS added to page', 'amp' ); ?>">
-							<?php echo esc_html( round( ( $percentage ) * 100 ) ) . '%'; ?>
-						</meter>
+						<?php if ( $denominator > 0 ) : ?>
+							<?php $percentage = $stylesheet['final_size'] / $denominator; ?>
+							<meter value="<?php echo esc_attr( $stylesheet['final_size'] ); ?>" min="0" max="<?php echo esc_attr( $included_final_size + $excluded_final_size ); ?>" title="<?php esc_attr_e( 'Stylesheet bytes of total CSS added to page', 'amp' ); ?>">
+								<?php echo esc_html( round( ( $percentage ) * 100 ) ) . '%'; ?>
+							</meter>
+						<?php else : ?>
+							included/excluded final sizes are zero
+						<?php endif; ?>
 					</td>
 					<td class="column-priority">
 						<?php echo esc_html( $stylesheet['priority'] ); ?>

[westonruter]

@amarinediary Did you find the cause of the problem?

[amarinediary]

Yes sorry, indeed, apparently not properly hiding the admin bar was trouble shooting with the amp plugin. You did answer that question perfectly, and I feel ashamed for opening it !