The error 'Failed to parse JSON response: Expecting value: line 1 column 1 (char 0)' is a strong indicator that the XSIAM integration received something other than valid JSON at the very beginning of the response. This often happens when an API key is invalid (A) or the endpoint is unreachable (B) because the server might return an HTML error page (like a 401 Unauthorized or a 404 Not Found) or a plain text error instead of the expected JSON. The JSON parser then tries to parse this non-JSON content and fails immediately. While a bug in parsing logic (D) is possible, the 'line 1 column 1' error points to the very first character, suggesting the entire response is not JSON. Querying for a non-existent indicator (E) would typically result in a valid JSON response with an empty result set or a specific API error code within the JSON, not a parsing failure of the response itself.