A non-serializable value was detected in the state: redux toolkit - node.js

Question

I am trying to implement Redux toolkit store in a react native application. It is my first time. I am using axios to make requests to the API.
I am getting this error on a post request:
A non-serializable value was detected in the state, in the path: `user`. Value: {"_A": null,
"_x": 0, "_y": 0, "_z": null}
Take a look at the reducer(s) handling this action type: userreg/fulfilled.
Here are my codes:
const initialState={
token: '',
session: '',
loading: false,
}
export const logInUser = createAsyncThunk('userreg', async(name, thunkAPI)=>{
const {user_username, user_password} = name
//const m = JSON.stringify(name)
const res = await axios.post(`${BASE_URL}/login`,
{
user_username, user_password
}
)
//console.log(res.data)
return res.data
})
const userSlice = createSlice({
name: 'user',
initialState,
reducers:{
addSession:(state, action)=>{
state.session = AsyncStorage.getItem('sessionId')
},
addToken:(state, action)=>{
state.token = AsyncStorage.getItem('token')
}
},
extraReducers: (builders)=>{
builders.addCase(logInUser.pending, (state, action)=>{
state.loading = true
})
builders.addCase(logInUser.fulfilled, async(state, {payload})=>{
console.log(payload, 'slode ier')
state.loading = false
state.token = payload.userToken;
state.session = payload.session;
await AsyncStorage.setItem('sessionId', payload.session);
await AsyncStorage.setItem('token', payload.userToken)
})
}
})
export default userSlice.reducer;
const handleUserLog = async ()=>{
const logDetails = {
user_username: userLogin.user_username,
user_password: userLogin.user_password,
}
dispatch(logInUser(logDetails))
}
When I implemented the same code with fetch instead of axios to make the same request to the API, it didn't give this error.