fix: wrap non-JSON decisions responses in DecisionsResponseValidationError

transform_decisions_response validated the raw body with validate_json outside
the try/except, so a non-JSON upstream body (e.g. an HTML error page) raised an
unhandled pydantic ValidationError. Move validate_json inside the try so a
malformed body surfaces as DecisionsResponseValidationError, like a schema
mismatch in parse_response.

Fixes #48660

litellm/llms/base_llm/decisions/transformation.py

@@ -657,8 +657,8 @@ class BaseDecisionsConfig(ABC):
         raw_response: httpx.Response,
         request: DecisionsIRRequest,
     ) -> DecisionsIRResponse:
-        payload: Final[object] = _PAYLOAD_ADAPTER.validate_json(raw_response.content)
         try:
+            payload: Final[object] = _PAYLOAD_ADAPTER.validate_json(raw_response.content)
             return self.parse_response(payload, request)
         except ValidationError as error:
             raise DecisionsResponseValidationError(

tests/unit/llms/base_llm/decisions/test_transform_decisions_response_non_json.py

@@ -0,0 +1,26 @@
+from typing import cast
+
+import httpx
+import pytest
+
+from litellm.llms.base_llm.decisions.transformation import (
+    BaseDecisionsConfig,
+    DecisionsResponseValidationError,
+)
+from litellm.types.decisions import DecisionsIRRequest
+
+
+def test_transform_decisions_response_wraps_non_json_body():
+    """Regression for #48660: a non-JSON response body raised an unhandled
+    pydantic ValidationError because `validate_json` ran outside the
+    try/except. It must surface as DecisionsResponseValidationError instead."""
+    config = BaseDecisionsConfig()
+    raw_response = httpx.Response(status_code=502, content=b"<html>Bad Gateway</html>")
+
+    with pytest.raises(DecisionsResponseValidationError):
+        config.transform_decisions_response(
+            model="jev-latest",
+            custom_llm_provider="systemone",
+            raw_response=raw_response,
+            request=cast(DecisionsIRRequest, None),
+        )