from fastapi import FastAPI
from fastapi.responses import JSONResponse
from pydantic import BaseModel


class Item(BaseModel):
    id: str
    value: str


class Message(BaseModel):
    message: str


app = FastAPI()


@app.get("/items/{item_id}", response_model=Item, responses={"default": {"model": Message}})
async def read_item(item_id: str):
    if item_id == "foo":
        return {"id": "foo", "value": "there goes my hero"}
    else:
        return JSONResponse(status_code=404, content={"message": "Item not found"})

Traceback (most recent call last):
  File "<stdin>", line 19, in <module>
  File "/Users/matnowak/.pyenv/versions/3.9.11/envs/radkit3.9/lib/python3.9/site-packages/fastapi/routing.py", line 622, in decorator
    self.add_api_route(
  File "/Users/matnowak/.pyenv/versions/3.9.11/envs/radkit3.9/lib/python3.9/site-packages/fastapi/routing.py", line 561, in add_api_route
    route = route_class(
  File "/Users/matnowak/.pyenv/versions/3.9.11/envs/radkit3.9/lib/python3.9/site-packages/fastapi/routing.py", line 418, in __init__
    assert is_body_allowed_for_status_code(
  File "/Users/matnowak/.pyenv/versions/3.9.11/envs/radkit3.9/lib/python3.9/site-packages/fastapi/utils.py", line 24, in is_body_allowed_for_status_code
    current_status_code = int(status_code)
ValueError: invalid literal for int() with base 10: 'default'

invalid literal for int() with base 10: 'default'