A logical error in the PHP SDKs being generated lead to a variable, _httpContext, being undefined in some cases. This resulted in a Fatal error when an APIException was expected to be thrown.
Please regenerate your PHP SDK to get the bug fix.
Details​
The PHP interpreter reported this problem as something like
Notice: Undefined variable _httpContext in ...
Fatal error: Call to a member function getResponse() on null in ...
This was due to _httpContext being defined in an if block, which was a logical error. Regenerating your PHP SDK should fix this bug.