diff --git a/src/together/abstract/api_requestor.py b/src/together/abstract/api_requestor.py
index e956bb3a..5360bab3 100644
--- a/src/together/abstract/api_requestor.py
+++ b/src/together/abstract/api_requestor.py
@@ -335,19 +335,14 @@ def handle_error_response(
         rcode: int,
         stream_error: bool = False,
     ) -> Exception:
-        try:
-            assert isinstance(resp.data, dict)
-            error_resp = resp.data.get("error")
-            assert isinstance(
-                error_resp, dict
-            ), f"Unexpected error response {error_resp}"
-            error_data = TogetherErrorResponse(**(error_resp))
-        except (KeyError, TypeError):
+        error_resp = resp.data.get("error") if isinstance(resp.data, dict) else None
+        if not isinstance(error_resp, dict):
             raise error.JSONError(
                 "Invalid response object from API: %r (HTTP response code "
                 "was %d)" % (resp.data, rcode),
                 http_status=rcode,
             )
+        error_data = TogetherErrorResponse(**error_resp)
 
         utils.log_info(
             "Together API error received",
diff --git a/tests/unit/test_error_response_handling.py b/tests/unit/test_error_response_handling.py
new file mode 100644
index 00000000..0624f2f4
--- /dev/null
+++ b/tests/unit/test_error_response_handling.py
@@ -0,0 +1,40 @@
+import pytest
+
+from together.abstract.api_requestor import APIRequestor
+from together.error import InvalidRequestError, JSONError, RateLimitError
+from together.together_response import TogetherResponse
+
+
+class TestHandleErrorResponse:
+    def test_detail_style_body_raises_json_error(self):
+        """
+        FastAPI-style error bodies ({"detail": ...}) have no "error" object.
+        The SDK must raise JSONError, not a raw AssertionError.
+        """
+        resp = TogetherResponse({"detail": "Not Found"}, {})
+
+        with pytest.raises(JSONError):
+            APIRequestor.handle_error_response(resp, 404)
+
+    def test_non_dict_error_field_raises_json_error(self):
+        resp = TogetherResponse({"error": "bad request"}, {})
+
+        with pytest.raises(JSONError):
+            APIRequestor.handle_error_response(resp, 400)
+
+    def test_non_dict_body_raises_json_error(self):
+        resp = TogetherResponse(["unexpected", "list"], {})
+
+        with pytest.raises(JSONError):
+            APIRequestor.handle_error_response(resp, 500)
+
+    def test_valid_error_body_maps_status_codes(self):
+        body = {"error": {"message": "rate limited", "type": "rate_limit"}}
+        resp = TogetherResponse(body, {})
+
+        assert isinstance(
+            APIRequestor.handle_error_response(resp, 429), RateLimitError
+        )
+        assert isinstance(
+            APIRequestor.handle_error_response(resp, 400), InvalidRequestError
+        )