willy.club/app/WillySoft/Http/ErrorHandler.php

<?php

namespace WillySoft\Http;

/**
 * Captures errors and exceptions thrown by your application and renders them to the user
 */
abstract class ErrorHandler 
{
    /**
     * Array of strings containing HTML error and exception messages
     */
    private static array $error_messages = [];

    /**
     * Start capturing output to be replaced, set error and exception handlers and register shutdown function.
     * 
     * On capturing an error or exception the callback will be called with an array of strings containing HTML error
     * messages as an argument.
     */
    public static function register(callable $callback)
    {
        ob_start();

        set_error_handler(function($errno, $errstr, $errfile, $errline) {
            $errstr = htmlspecialchars($errstr);
            self::$error_messages[] = "<b>Error[$errno]:</b> $errstr in <b>$errfile</b> at line <b>$errline</b>";
        });

        set_exception_handler(function($exception) {
            self::$error_messages[] = "<b>Uncaught Exception:</b> " . $exception;
        });

        register_shutdown_function(function() use(&$callback) {
            if (!self::$error_messages) {
                return; 
            }

            // remove current output to be replaced by error page
            ob_end_clean();

            http_response_code(500);
            header_remove();

            $callback(self::$error_messages);
        });
    }
}