Description:
------------
Manual says:
"As of PHP 5.4 string offsets have to either be integers or integer-like strings, otherwise a warning will be thrown. Previously an offset like "foo" was silently cast to 0."

That warning will suppressed by wrapping variable in isset() or empty();

http://3v4l.org/MEldp


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

$a = 'foo';
var_dump($a['bar']); // warning
var_dump(empty($a['bar'])); // no warning
var_dump(isset($a['bar'])); // no warning