Merge pull request SimpleMachines#7821 from Sesquipedalian/truncated_…

…itemcode

Fixes uninitialized string offset error when parsing broken itemcode

Sources/Subs.php

@@ -3482,7 +3482,7 @@ function($matches) use ($schemes)
 		}
 
 		// Item codes are complicated buggers... they are implicit [li]s and can make [list]s!
-		if ($smileys !== false && $tag === null && isset($itemcodes[$message[$pos + 1]]) && $message[$pos + 2] == ']' && !isset($disabled['list']) && !isset($disabled['li']))
+		if ($smileys !== false && $tag === null && isset($itemcodes[$message[$pos + 1]], $message[$pos + 2]) && $message[$pos + 2] == ']' && !isset($disabled['list']) && !isset($disabled['li']))
 		{
 			if ($message[$pos + 1] == '0' && !in_array($message[$pos - 1], array(';', ' ', "\t", "\n", '>')))
 				continue;