illegal operation on a directory, read

```
var path = RNFS.DocumentDirectoryPath + '/test.txt';
// write the file
RNFS.writeFile(path, 'Lorem ipsum dolor sit amet', 'utf8')
.then((success) => {
console.log('FILE WRITTEN!');
})
.catch((err) => {
console.log('err:',err.message);
});
```

Running on the android simulator, keep reporting the following error

`err: EISDIR: illegal operation on a directory, read '/data/user/0/****/files/test.txt'`

Please help me