Improve JSON error payload fallback message extraction

Co-authored-by: Shri Sukhani <shrisukhani@users.noreply.github.com>

Author: cursoragent

hyperbrowser/transport/error_utils.py

@@ -29,10 +29,10 @@ def extract_error_message(response: httpx.Response, fallback_error: Exception) -
             message = error_data.get(key)
             if message is not None:
                 return _stringify_error_value(message)
-        return response.text or str(fallback_error)
+        return _stringify_error_value(error_data)
     if isinstance(error_data, str):
         return error_data
-    return _stringify_error_value(response.text or str(fallback_error))
+    return _stringify_error_value(error_data)
 
 
 def extract_request_error_context(error: httpx.RequestError) -> tuple[str, str]:

tests/test_transport_response_handling.py

@@ -211,6 +211,33 @@ async def run() -> None:
     asyncio.run(run())
 
 
+def test_sync_handle_response_with_dict_without_message_keys_stringifies_payload():
+    transport = SyncTransport(api_key="test-key")
+    try:
+        response = _build_response(500, '{"code":"UPSTREAM_FAILURE","retryable":false}')
+
+        with pytest.raises(HyperbrowserError, match='"code": "UPSTREAM_FAILURE"'):
+            transport._handle_response(response)
+    finally:
+        transport.close()
+
+
+def test_async_handle_response_with_non_dict_json_stringifies_payload():
+    async def run() -> None:
+        transport = AsyncTransport(api_key="test-key")
+        try:
+            response = _build_response(500, '[{"code":"UPSTREAM_FAILURE"}]')
+
+            with pytest.raises(
+                HyperbrowserError, match='\\[\\{"code": "UPSTREAM_FAILURE"\\}\\]'
+            ):
+                await transport._handle_response(response)
+        finally:
+            await transport.close()
+
+    asyncio.run(run())
+
+
 def test_sync_transport_post_wraps_request_errors_with_url_context():
     transport = SyncTransport(api_key="test-key")
     original_post = transport.client.post