You can safely use isset to check properties and subproperties of objects directly. So instead of writing
 isset($abc) && isset($abc->def) && isset($abc->def->ghi)
or in a shorter form
 isset($abc, $abc->def, $abc->def->ghi)
you can just write
 isset ($abc->def->ghi)
without raising any errors, warnings or notices.
Examples
<?php
 $abc = (object) array("def" => 123);
 var_dump(isset($abc)); // bool(true)
 var_dump(isset($abc->def)); // bool(true)
 var_dump(isset($abc->def->ghi)); // bool(false)
 var_dump(isset($abc->def->ghi->jkl)); // bool(false)
 var_dump(isset($def)); // bool(false)
 var_dump(isset($def->ghi)); // bool(false)
 var_dump(isset($def->ghi->jkl)); // bool(false)
 var_dump($abc); // object(stdClass)#1 (1) { ["def"] => int(123) }
 var_dump($abc->def); // int(123)
 var_dump($abc->def->ghi); // null / E_NOTICE: Trying to get property of non-object
 var_dump($abc->def->ghi->jkl); // null / E_NOTICE: Trying to get property of non-object
 var_dump($def); // null / E_NOTICE: Trying to get property of non-object
 var_dump($def->ghi); // null / E_NOTICE: Trying to get property of non-object
 var_dump($def->ghi->jkl); // null / E_NOTICE: Trying to get property of non-object
?>