WordPress Error Handler with debug backtrace

wp-error-handler.php

<?php
/*
Plugin Name: WordPress Error Handler
Description: An error handler with backtrace (not just for fatal errors).
Author: Earl Peter G
Author URI: https://www.earlpeter.com
Version: 0.3
License: Licensed under the Apache License, Version 2.0
http://www.apache.org/licenses/LICENSE-2.0
*/

// define( 'WP_DEBUG', true );            // Set to enable
// define( 'WP_DEBUG_DISPLAY', true );    // Set to display errors and warnings
// define( 'WP_DEBUG_LOG', true );        // Set to log errors and warnings

// Do not access file directly!
if (!defined('WPINC')) { die; }

if (!class_exists ('EarlPeter_WP_Error_Handler')) {
    class EarlPeter_WP_Error_Handler {
        public static function handleError($errno, $errstr, $errfile, $errline, $errcontext) {
            if (!(error_reporting() & $errno)) {
                // This error code is not included in error_reporting, so let it fall
                // through to the standard PHP error handler
                return false;
            }

            // These are default values for a single trace
            // To prevent errors when a trace ommits some values
            $defaults = ['line' => '', 'file' => '', 'class' => '', 'function' => ''];
            $errfile = self::cleanFilePath($errfile);
            $errname = self::errorCodeToString($errno);
            $out = "\n$errname ($errno): $errstr\n";
            $out .= "#0 <b>{main}</b> at $errfile:$errline\n";

            $trace = debug_backtrace();
            // skip current function and require() in /index.php
            for($i = 1; $i < count($trace) - 1; $i++) {
                $sf = (object)shortcode_atts($defaults, $trace[$i]);
                $index = $i;
                $file = self::cleanFilePath($sf->file);

                $caller;
                if(!empty($sf->class) && !empty($sf->function))
                    $caller = $sf->class . "::" . $sf->function . "()";
                elseif(!empty($sf->function))
                    $caller = $sf->function . "()";
                else
                    $caller = "{main}";

                    $out .= "#$index <b>$caller</b> at $file:{$sf->line}\n";
            }
            if (WP_DEBUG_DISPLAY) echo nl2br($out);
            if (WP_DEBUG_LOG) error_log($out);

            return true;
        }

        /**
         * Removes root path of WordPress from a given directory.
         * @param string $path
         * @return string
         */
        private static function cleanFilePath($path){
            return str_replace(ABSPATH, '/', $path);
        }

        /**
         * Gets the equivalent error code in string
         * @param int $code
         * @return string
         */
        private static function errorCodeToString($code) {
            $errors = array(
                1 => 'ERROR',
                2 => 'WARNING',
                4 =>  'PARSE',
                8 =>  'NOTICE',
                16 =>  'CORE ERROR',
                32 =>  'CORE WARNING',
                64 => 'COMPILE ERROR',
                128 => 'COMPILE WARNING',
                256 => 'USER ERROR',
                512 => 'USER WARNING',
                1024 => 'USER NOTICE',
                2048 => 'STRICT',
                4096 => 'RECOVERABLE ERROR',
                8192 => 'DEPRECATED',
                16384 => 'USER DEPRECATED',
            );
            if (isset($errors[$code])) return $errors[$code];
            else return 'UNKNOWN ERROR';
        }
    }

    if (WP_DEBUG) set_error_handler('EarlPeter_WP_Error_Handler::handleError');
}