chore: import upstream snapshot with attribution

python/mlc_llm/protocol/error_protocol.py

@@ -0,0 +1,35 @@
+"""Error protocols in MLC LLM"""
+
+from http import HTTPStatus
+from typing import Optional
+
+import fastapi
+from pydantic import BaseModel
+
+
+class BadRequestError(ValueError):
+    """The exception for bad requests in engines."""
+
+    def __init__(self, *args: object) -> None:
+        super().__init__(*args)
+
+
+class ErrorResponse(BaseModel):
+    """The class of error response."""
+
+    object: str = "error"
+    message: str
+    code: Optional[int] = None
+
+
+def create_error_response(status_code: HTTPStatus, message: str) -> fastapi.responses.JSONResponse:
+    """Create a JSON response that reports error with regarding the input message."""
+    return fastapi.responses.JSONResponse(
+        ErrorResponse(message=message, code=status_code.value).model_dump_json(by_alias=True),
+        status_code=status_code.value,
+    )
+
+
+async def bad_request_error_handler(_request: fastapi.Request, e: BadRequestError):
+    """The handler of BadRequestError that converts an exception into error response."""
+    return create_error_response(status_code=HTTPStatus.BAD_REQUEST, message=e.args[0])