Backtrace on fatal_error in PHP

backtrace.php

<?php
function shutdown() {
    $error = error_get_last();
    if ($error['type'] === E_ERROR) {
        // fatal error has occured
        $trace = array_reverse($GLOBALS['dbg_stack']);
        array_pop($trace);
        if(php_sapi_name() == 'cli') {
            echo 'Backtrace for: \'' . $error['message'] . '\' at ' . $error['file'] . ':' . $error['line'] . ':' . "\n";
            foreach($trace as $item)
                echo '  ' . (isset($item['file']) ? $item['file'] : '<unknown file>') . ':' . (isset($item['line']) ? $item['line'] : '<unknown line>') . ' calling ' . $item['function'] . '()' . "\n";
        } else {
            echo '<p class="error_backtrace">' . "\n";
            echo '  Backtrace for: \'' . $error['message'] . '\' at ' . $error['file'] . ':' . $error['line'] . ':' . "\n";
            echo '  <ol>' . "\n";
            foreach($trace as $item)
                echo '    <li>' . (isset($item['file']) ? $item['file'] : '<unknown file>') . ':' . (isset($item['line']) ? $item['line'] : '<unknown line>') . ' calling ' . $item['function'] . '()</li>' . "\n";
            echo '  </ol>' . "\n";
            echo '</p>' . "\n";
        }
        
    }
}
register_shutdown_function('shutdown');

function write_dbg_stack() {
    $GLOBALS['dbg_stack'] = debug_backtrace();
}
register_tick_function('write_dbg_stack');
declare(ticks=1);