fix: remove dead code and add failing hitl error scenarios

Author: mjschock

tests/fake_model.py

@@ -128,8 +128,11 @@ async def get_response(
             for item in output:
                 if isinstance(item, dict) and item.get("type") == "apply_patch_call":
                     import json
+
                     operation = item.get("operation", {})
-                    operation_json = json.dumps(operation) if isinstance(operation, dict) else str(operation)
+                    operation_json = (
+                        json.dumps(operation) if isinstance(operation, dict) else str(operation)
+                    )
                     converted_item = ResponseCustomToolCall(
                         type="custom_tool_call",
                         name="apply_patch",