Helper function to show a WordPress admin notice

admin-notify.php

<?php
function notify(string $message, string $noticeType, array $allowedMarkup = []): void
{
    $callback = function () use ($message, $noticeType, $allowedMarkup) {
        ?>
        <div class="notice notice-<?= \sanitize_html_class($noticeType) ?>">
            <p><?= \wp_kses($message, $allowedMarkup) ?></p>
        </div>
        <?php
    };
    
    if (\did_action('admin_notices') && \defined('WP_DEBUG') && WP_DEBUG) {
        throw new \LogicException('Cannot call `admin_notices`, the action has been executed.')
    }
    
    if (\doing_action('admin_notices')) {
       $callback();
       return;
    }
    
    \add_action('admin_notices', $callback);
}