[Sentinel-Intel] SentinelApiHandler _send_request() returns None when an exception is caught

[Powlinett]

Description

When an exception is caught in _send_request() function, the returned value is None. As some responses from Sentinel contain no content, we can't distinct if the None value is expected or if an error occurred, which lead to TypeError: data is not subscriptable kind of errors in functions using _send_request() internally.

Environment

1. OS (where OpenCTI server runs): Windows 11
2. OpenCTI version: OpenCTI 6.5
3. OpenCTI client: client-python 6.5
4. Other environment details:

Expected Output

Raised exception in _send_request should stop the execution of process_message() gracefully

Actual Output

process_message() execution is stopped by the TypeError resulting from returning None when an error is caught.