Description:
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I think that json_decode have problem with incorrect data passed as parameter;

Reproduce code:
---------------
$post = " ";
$data = json_decode($post);
some other code here

Expected result:
----------------
empty $data or similar

Actual result:
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for every line of code below (even if it's commented out) will show

Notice: Trying to get property of non-object in file.php on line 54
Notice: Trying to get property of non-object in file.php on line 55
etc..