Description:
------------
Array $context passed to custom error handler is non-standard because contains string numeric keys. Example: https://3v4l.org/BR04H


Because $context is deprecated, there is no need to fix it, I just wanted to document it.

Test script:
---------------
<?php

set_error_handler(function ($errno, $errstr, $errfile, $errline, $errcontext) {
	var_dump($context);
});

$a = 1;
$$a = 2;


Expected result:
----------------
array(3) { [1]=> int(2), ... }

Actual result:
--------------
array(3) { ["1"]=> int(2), ... }