Description:
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---
From manual page: http://www.php.net/language.types.array
---
I accidentally discovered that when you try to call a NULL variable as an array, PHP will simply return NULL without triggering any form of error.
I don't believe that this is intended behaviour, as calling an undefined offset in an array causes a warning. 

My sincere apologies if this bug has been reported earlier, I spent quite a while searching in and outside of php.net to no avail.

Test script:
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<?php 

error_reporting(-1);

$array = array();

// This will return NULL and trigger an 'undefined offset' notice.
var_dump($array[1]);

// This will return NULL and trigger an 'undefined variable' notice.
var_dump($undefined[3]); 
var_dump($undefined[1]);

$null_var = null;

// This, however, will return NULL and give no error.
var_dump($null_var[1]);

Expected result:
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PHP Notice:  Undefined offset: 1 in /var/www/null.php on line 8
NULL
PHP Notice:  Undefined variable: undefined in /var/www/null.php on line 11
NULL
PHP Notice:  Undefined variable: undefined in /var/www/null.php on line 12
NULL
NULL