Uncaught TypeError invoking Site Editor

[bobbingwide]

On s.b/wordpress I clicked on Appearance > Site Editor and ended up with this Fatal.
Failed in 6.3, also fails in 6.2 and 6.1

Fatal error: Uncaught TypeError: implode(): Argument #2 ($array) must be of type ?array, string given in C:\apache\htdocs\wordpress\wp-content\themes\fizzie\includes\navigation-link.php:82
Stack trace:

#0 C:\apache\htdocs\wordpress\wp-content\themes\fizzie\includes\navigation-link.php(82): implode(' ', ' menu-item menu...')
#1 C:\apache\htdocs\wordpress\wp-content\themes\fizzie\includes\navigation-link.php(12): fizzie_fiddle_block_context(Array, Object(WP_Block))
#2 C:\apache\htdocs\wordpress\wp-includes\class-wp-block.php(258): fizzie_render_block_core_navigation_link(Array, '', Object(WP_Block))
#3 C:\apache\htdocs\wordpress\wp-includes\blocks.php(1133): WP_Block->render()
#4 C:\apache\htdocs\wordpress\wp-includes\blocks.php(1171): render_block(Array)
#5 C:\apache\htdocs\wordpress\wp-includes\class-wp-hook.php(310): do_blocks('<!-- wp:navigat...')
#6 C:\apache\htdocs\wordpress\wp-includes\plugin.php(205): WP_Hook->apply_filters('<!-- wp:navigat...', Array)
#7 C:\apache\htdocs\wordpress\wp-includes\rest-api\endpoints\class-wp-rest-posts-controller.php(1864): apply_filters('the_content', '<!-- wp:navigat...')
#8 C:\apache\htdocs\wordpress\wp-includes\rest-api\endpoints\class-wp-rest-posts-controller.php(385): WP_REST_Posts_Controller->prepare_item_for_response(Object(WP_Post), Object(WP_REST_Request))
#9 C:\apache\htdocs\wordpress\wp-includes\rest-api\class-wp-rest-server.php(1188): WP_REST_Posts_Controller->get_items(Object(WP_REST_Request))
#10 C:\apache\htdocs\wordpress\wp-includes\rest-api\class-wp-rest-server.php(1035): WP_REST_Server->respond_to_request(Object(WP_REST_Request), '/wp/v2/navigati...', Array, NULL)
#11 C:\apache\htdocs\wordpress\wp-includes\rest-api.php(545): WP_REST_Server->dispatch(Object(WP_REST_Request))
#12 C:\apache\htdocs\wordpress\wp-includes\rest-api.php(2911): rest_do_request(Object(WP_REST_Request))
#13 [internal function]: rest_preload_api_request(Array, '/wp/v2/navigati...')
#14 C:\apache\htdocs\wordpress\wp-includes\block-editor.php(743): array_reduce(Array, 'rest_preload_ap...', Array)
#15 C:\apache\htdocs\wordpress\wp-admin\site-editor.php(116): block_editor_rest_api_preload(Array, Object(WP_Block_Editor_Context))
#16 {main}
  thrown in <b>C:\apache\htdocs\wordpress\wp-content\themes\fizzie\includes\navigation-link.php</b> on line <b>82</b><br />

Additionally, the trace log shows a couple of Warnings from the code that's sending the fatal error email.

C:\apache\htdocs\wordpress\wp-content\plugins\oik-bwtrace\includes\bwtrace-actions.php(286:2) bw_trace_error_handler(1) 1394 1 2023-09-11T10:46:40+00:00 2.839904 0.065048 cf=the_content 73246 137 18395 27262976/27262976 1024M F=1682 err Array

    [0] => (integer) 2
    [1] => (string) "Warning: Trying to access array offset on value of type bool"
    [2] => (string) "C:\apache\htdocs\wordpress\wp-includes\class-wp-recovery-mode-email-service.php"
    [3] => (integer) 367

C:\apache\htdocs\wordpress\wp-content\plugins\oik-bwtrace\includes\bwtrace-actions.php(287:64) bw_trace_error_handler(2) 1395 1 2023-09-11T10:46:40+00:00 2.840061 0.000157 cf=the_content 73246 137 18395 27262976/27262976 1024M F=1682 errcontext 
0. bw_lazy_backtrace C:\apache\htdocs\wordpress\wp-content\plugins\oik-bwtrace\libs\bwtrace.php:108 0
1. bw_backtrace C:\apache\htdocs\wordpress\wp-content\plugins\oik-bwtrace\includes\bwtrace-actions.php:293 0
2. bw_trace_error_handler(2,Trying to access array offset on value of type bool,C:\apache\htdocs\wordpress\wp-includes\class-wp-recovery-mode-email-service.php,367) C:\apache\htdocs\wordpress\wp-includes\class-wp-recovery-mode-email-service.php:367 4
3. get_debug(array) C:\apache\htdocs\wordpress\wp-includes\class-wp-recovery-mode-email-service.php:150 1
4. send_recovery_mode_email(86400,array,array) C:\apache\htdocs\wordpress\wp-includes\class-wp-recovery-mode-email-service.php:62 3
5. maybe_send_recovery_mode_email(86400,array,array) C:\apache\htdocs\wordpress\wp-includes\class-wp-recovery-mode.php:185 3
6. handle_error(array) C:\apache\htdocs\wordpress\wp-includes\class-wp-fatal-error-handler.php:53 1
7. handle C:\apache\htdocs\wordpress\wp-includes\class-wp-fatal-error-handler.php:0 0

[bobbingwide]

The code was failing since $attributes['className'] was already a string, so did not need to be imploded.

[className] => (string) " menu-item menu-item-type-post_type menu-item-object-page"

Simplest solution was to check if it was an array before calling implode. If not, then assign the string directly.
This fixes the fatal.

I didn't check if the code was still necessary.