[Python] How to customize error response in FastAPI?

I have the following FastAPI backend:

from fastapi import FastAPI

app = FastAPI

class Demo(BaseModel):
content: str = None

@app.post("/demo")
async def demoFunc(demo):
return d.content


The issue is that when I send a request to this API with extra data like:

data = {"content":"some text here"}aaaa


or

data = {"content":"some text here"aaaaaa}

resp = requests.post(url, json=data)


it throws an error with status code 422 unprocessable entity error with Actual("some text here") and Extra("aaaaa") data in the return field in case of data = {"content":"some text here"}aaaa:

{
"detail": [
{
"loc": [
"body",
47
],
"msg": "Extra data: line 4 column 2 (char 47)",
"type": "value_error.jsondecode",
"ctx": {
"msg": "Extra data",
"doc": "{\n \"content\": \"some text here\"}aaaaa",
"pos": 47,
"lineno": 4,
"colno": 2
}
}
]
}


I tried to put the line app=FastAPI() in a try-catch block, however, it doesn't work. Is there any way I can handle this issue with own response instead of the above mentioned auto response? Something like this:

{"error": {"message": "Invalid JSON body"},
"status": 0}

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