ref(supergroups): extract helper for get-by-group-ids Seer call

[cvxluo]

Move the actual seer request for supergroups to its own helper. This is building up to serve a blended supergroup + issues endpoint.

[sentry-warden]

orjson.loads() on Seer API response lacks JSONDecodeError handling

The orjson.loads(response.data) call at line 40 parses the external Seer API response without catching orjson.JSONDecodeError. If Seer returns an HTML error page, empty body, or truncated JSON with a non-4xx status code (e.g., 200 with invalid content, or 3xx redirect), this will raise an unhandled exception. This matches Check 8 (Data Parsing & Deserialization) patterns where external APIs can return unexpected non-JSON responses.

Verification

Read the full file src/sentry/seer/supergroups/by_group.py and traced the data flow. The response comes from make_supergroups_get_by_group_ids_request() in src/sentry/seer/signed_seer_api.py which returns a BaseHTTPResponse from urllib3. Only status >= 400 is handled before JSON parsing. Confirmed orjson.loads() has no try/except wrapper. The endpoint in organization_supergroups_by_group.py only catches SeerApiError, not JSONDecodeError.

Suggested fix: Wrap orjson.loads() in try/except to handle malformed JSON responses from the Seer API

Suggested change

	return orjson.loads(response.data)
	import logging
	logger = logging.getLogger(__name__)
	try:
	return orjson.loads(response.data)
	except orjson.JSONDecodeError:
	logger.warning(
	"seer.supergroups.invalid_json_response",
	extra={
	"organization_id": organization.id,
	"response_status": response.status,
	},
	)
	raise SeerApiError("Invalid JSON response from Seer", 502)

Identified by Warden sentry-backend-bugs · 9PQ-N66