Fatal error in post-hierarchical-terms.php

[bobbingwide]

Detected while trying to view https://s.b/wp55/fizzie/category/block-news/

Notice: Trying to get property 'term_id' of non-object in C:\apache\htdocs\wp55\wp-content\plugins\gutenberg\build\block-library\blocks\post-hierarchical-terms.php on line 32

Notice: Trying to get property 'name' of non-object in C:\apache\htdocs\wp55\wp-content\plugins\gutenberg\build\block-library\blocks\post-hierarchical-terms.php on line 33

Fatal error: Uncaught Error: Object of class WP_Error could not be converted to string in
C:\apache\htdocs\wp55\wp-content\plugins\gutenberg\build\block-library\blocks\post-hierarchical-terms.php:33
Stack trace:
#0 C:\apache\htdocs\wp55\wp-content\plugins\gutenberg\build\block-library\blocks\post-hierarchical-terms.php(33): sprintf('...', Object(WP_Error), '')
#1 C:\apache\htdocs\wp55\wp-includes\class-wp-block.php(219): gutenberg_render_block_core_post_hierarchical_terms(Array, '', Object(WP_Block))
#2 C:\apache\htdocs\wp55\wp-includes\class-wp-block.php(211): WP_Block->render()
#3 C:\apache\htdocs\wp55\wp-includes\class-wp-block.php(211): WP_Block->render()
#4 C:\apache\htdocs\wordpress\wp-content\themes\fizzie\functions.php(307): WP_Block->render(Array)
#5 C:\apache\htdocs\wordpress\wp-content\themes\fizzie\functions.php(263): fizzie_render_block_core_query_loop_main_query(Array, '', Object(WP_Block))
#6 C:\apache\htdocs\wp55\wp-includes\class-wp-block.php(219): fizzie_render_block_core_query_loop(Array, in C:\apache\htdocs\wp55\wp-content\plugins\gutenberg\build\block-library\blocks\post-hierarchical-terms.php on line 33

[bobbingwide]

Analysis

This is a problem in core/post-hierarchical-terms. It fails to detect the WordPress error issued by get_the_terms() when the taxonomy name is invalid.

C:\apache\htdocs\wp55\wp-content\plugins\gutenberg\build\block-library\blocks\post-hierarchical-terms.php(23:0) gutenberg_render_block_core_post_hierarchical_terms(4) 54 0 2020-11-10T12:28:55+00:00 0.206871 0.000335 cf=pre_render_block,pre_render_block 9089 40 58 2097152/2097152 256M F=420 pht WP_Error Object
(
    [errors] => Array
        (
            [invalid_taxonomy] => Array
                (
                    [0] => Invalid taxonomy.
                )

        )

    [error_data] => Array
        (
        )

    [additional_data:protected] => Array
        (
        )

In my example the taxonomy was letters, but this was not registered in that particular site.

Fix

In render_block_core_post_hierarchical_terms() add a test after calling get_the_terms().

$post_hierarchical_terms = get_the_terms( $block->context['postId'], $attributes['term'] );
if ( is_wp_error( $post_hierarchical_terms ) ) {
        return '';
}

[bobbingwide]

I've raised the issue on Gutenberg. Now I'll develop a local workaround and add it to #25

[bobbingwide]

Workaround is no longer used - it's commented out. But I haven't deleted the code. Closing anyway.