PHP - Highlight PHP errors

auto_prepend_file.php

<?php

function checkErrors()
{
    $errorMessage  = 'This web page contains errors! Go and check it out in the error_log (' . ini_get('error_log') . ').';
    $outputContent = ob_get_clean();
    $errors        = error_get_last();
    
    // If there is at least one error...
    if (!empty($errors)) {
        // ... and is not an AJAX call ...
        if (!$GLOBALS['isAjaxRequest']) {
            // ... add a div to the web page.
            $outputContent .= '<div style="background-color: #F00; position: absolute; padding: 10px; font-size: 13px; color: #FFF; font-weight: bold; width: 100%; text-align: center; top: 0px; text-decoration: blink;">' . $errorMessage . '</div>';
            $outputContent .= '<style type="text/css">html { margin-top: 30px !important; }</style>';
        } else {
            // ... adapt to show an error message in case of AJAX call.
        }
    }

    // Then print the entire response.
    echo $outputContent;
}

// Execute the function at the end of the execution.
register_shutdown_function('checkErrors');

// Check if the HTTP request is an AJAX call.
$GLOBALS['isAjaxRequest'] = !empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest';

// Start the output buffering
ob_start();

?>