Can't convert null or undefined with React Hooks - reactjs

Question

I have a state that I set with Hooks in react, like this :
useEffect(() => {
if (uid !== null) {
axios.get(`${process.env.REACT_APP_API_URL}api/balance/${uid}`)
.then((res) => {
setUserWalletIncomes(res.data[0].incomes)
})
}
}, [uid])
This state, to be clear, give me this :
Everything works fine I can delete my incomes etc.
Problem is, when I delete the last income (which makes the state empty), I have this error and a page blank :
TypeError: Cannot convert undefined or null to object
Here is my request to delete :
const handleDeleteIncome = (key) => {
let data = { [key]: "" }
axios({
method: "delete",
url: `${process.env.REACT_APP_API_URL}api/balanceOneIncome/${uid}`,
data: data
}).then((res) => {
if {(userWalletIncomes === null) setUserWalletIncomes({})}
setUserWalletIncomes(res.data[0].incomes)
setformIncomes(false)
})
}
I tried to add a condition : if {(userWalletIncomes === null) setUserWalletIncomes({})}, but I still have the same problem.
Can someone help me with this ?
[EDIT]
My state is initialized like this :
const [userWalletIncomes, setUserWalletIncomes] = useState({})
PS : If I reload the page, everything is fine.

Answer 1

Is this the problem? (I am assuming you don't really have the weird {} brace positioning as in your post?)
You have this:
if (userWalletIncomes === null) { setUserWalletIncomes({}) }
setUserWalletIncomes(res.data[0].incomes)
But after you call setUserWalletIncomes({}) you fall through and immediately call it again with the null value in the next line. Maybe you just need to explicitly return after setting it to the empty object? Or, to simplify, you could remove that conditional and do this instead:
setUserWalletIncomes(res.data[0].incomes || {})

Answer 2

Answer, if it helps someone, is this :
const handleDeleteIncome = (key) => {
let data = { [key]: "" }
axios({
method: "delete",
url: `${process.env.REACT_APP_API_URL}api/balanceOneIncome/${uid}`,
data: data
}).then((res) => {
if (res.data[0].incomes) {
setUserWalletIncomes(res.data[0].incomes)
} else {
setUserWalletIncomes({})
}
})
}
Just a condition that tells if response is null, then set the state to an empty object.