Description:
------------
Using array assignment on a string reference usually causes a fatal 'Illegal string offset' error.

PHP hang when a using an error handler that converts errors to exceptions.

This only effects invalid array access on references. An illegal array access on a non reference variable causes the exception to be emitted. 



Test script:
---------------
set_error_handler(function ($severity, $message, $file, $line) {
    throw new \Exception($message);
});

$x = "foo";
$y = &$x["bar"];


Expected result:
----------------
PHP Fatal error:  Uncaught Exception: Illegal string offset 'bar' in ...