Error when activating plugin

I am trying to create a custom plugin and keep getting the following error when activating it:

Plugin could not be activated because it triggered a fatal error.

The plugin does seem to activate however, but obviously this error raises an eyebrow. I tested with a very basic custom plugin and I am even able to reproduce it by activating the Hello Dolly plugin.

I enabled debug mode and got the following log:

[Thu Aug 29 13:09:08.622051 2024] [php:error] [pid 67:tid 67] [client 192.168.65.1:16990] PHP Fatal error:  Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, function "after_otter_activation" not found or invalid function name in /var/www/html/wp-includes/class-wp-hook.php:326\nStack trace:\n#0 /var/www/html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters('', Array)\n#1 /var/www/html/wp-includes/plugin.php(517): WP_Hook->do_action(Array)\n#2 /var/www/html/wp-admin/includes/plugin.php(730): do_action('activated_plugi...', 'hello.php', false)\n#3 /var/www/html/wp-admin/plugins.php(60): activate_plugin('hello.php', 'http://localhos...', false)\n#4 {main}\n  thrown in /var/www/html/wp-includes/class-wp-hook.php on line 326, referer: http://localhost:8000/wp-admin/plugins.php?plugin_status=all&paged=1&s

It seems to have some issue with the after_otter_activation function which is part of the theme.

Is this a bug and something that should be “ignored” for now?

Note: I am running WordPress locally via Docker.