flexible sync is not working

[letmetell]

I connected my mongodb cloud database with my using app id
and I haves some repeated error

`import React, { useEffect, useState } from 'react';
import { View, Text, TextInput, Button, FlatList, StyleSheet } from 'react-native';
import Realm from 'realm';

const TaskSchema = {
name: 'Task',
properties: {
_id: 'objectId',
title: 'string',
description: 'string',
completed: 'bool',
},
primaryKey: '_id',
};

const appConfig = {
id: '',
timeout: 10000,
};

export const realmApp = new Realm.App(appConfig);

export const realm = async () => {
const user = await realmApp.logIn(Realm.Credentials.anonymous());
const config = {
schema: [TaskSchema],
sync: {
user,
newRealmFileBehavior: {
type: 'openImmediately',
},
existingRealmFileBehavior: {
type: 'downloadBeforeOpen',
},
},
};
return Realm.open(config);
};

const App = () => {
const [tasks, setTasks] = useState([]);
const [newTaskTitle, setNewTaskTitle] = useState('');
const [newTaskDescription, setNewTaskDescription] = useState('');

useEffect(() => {
const getTasks = async () => {
const realmInstance = await realm();
const taskCollection = realmInstance.objects('Task');
setTasks(Array.from(taskCollection));
taskCollection.addListener(() => {
setTasks(Array.from(taskCollection));
});
};
getTasks();
}, []);

const createTask = async () => {
const realmInstance = await realm();
realmInstance.write(() => {
realmInstance.create('Task', {
_id: new Realm.BSON.ObjectId(),
title: newTaskTitle,
description: newTaskDescription,
completed: false,
});
});
setNewTaskTitle('');
setNewTaskDescription('');
};

const toggleTaskCompletion = async (taskId) => {
const realmInstance = await realm();
const task = realmInstance.objectForPrimaryKey('Task', taskId);
realmInstance.write(() => {
task.completed = !task.completed;
});
};

const deleteTask = async (taskId) => {
const realmInstance = await realm();
const task = realmInstance.objectForPrimaryKey('Task', taskId);
realmInstance.write(() => {
realmInstance.delete(task);
});
};

const renderItem = ({ item }) => (

{item.title}
{item.description}
<Button
title={item.completed ? 'Undo' : 'Complete'}
onPress={() => toggleTaskCompletion(item._id)}
/>
<Button title="Delete" onPress={() => deleteTask(item._id)} />

);

return (

Todo App

<TextInput
style={styles.input}
placeholder="Title"
value={newTaskTitle}
onChangeText={(text) => setNewTaskTitle(text)}
/>
<TextInput
style={styles.input}
placeholder="Description"
value={newTaskDescription}
onChangeText={(text) => setNewTaskDescription(text)}
/>


<FlatList
style={styles.taskList}
data={tasks}
renderItem={renderItem}
keyExtractor={(item) => item._id}
/>

);
};

const styles = StyleSheet.create({
container: {
flex: 1,
padding: 16,
justifyContent: 'center',
},
title: {
fontSize: 24,
fontWeight: 'bold',
marginBottom: 16,
},
inputContainer: {
marginBottom: 16,
},
input: {
marginBottom: 8,
padding: 8,
borderWidth: 1,
borderColor: 'gray',
},
taskList: {
flexGrow: 1,
},
taskItem: {
flexDirection: 'row',
justifyContent: 'space-between',
alignItems: 'center',
marginBottom: 8,
padding: 8,
borderWidth: 1,
borderColor: 'gray',
},
});

export default App;
`

when I run the code it gives this error
Possible Unhandled Promise Rejection (id: 0):
Error: Exception in HostFunction: partitionValue must be of type 'string', 'number', 'objectId', or 'null'.
Error: Exception in HostFunction: partitionValue must be of type 'string', 'number', 'objectId', or 'null'.
at exists (native)error many times pl someone help me quick as possible