Description:
------------
The documentation suggests that json_decode will only analyse down to the recursion level specified. But it does not say that when that happens it will just give up. 

However it would be better to alter the behaviour. It would be better if it analysed down to and returned results for the analysis down to the recursion level specified. e.g.

json_decode('[3,4,{"X":"Y"}]', false, 1);
should return
array(3) [
3
4
'{"X":"Y"}'
]

This would allow analysis in sections for large objects and various other useful purposes.
rather than null;