React-Redux: Cannot read property 'map' of undefined when deleting an item - reactjs

Question

I have an error after clicking the delete button saying:
Cannot read property 'map' of undefined.
I'm new in React Redux JS.
Please see my code below of my component reducers and actions:
Post.js
class Post extends Component {
constructor(){
super();
this.deletePost = this.deletePost.bind(this);
}
deletePost(postId){
this.props.deletePost(postId);
}
render(){
const postItems = this.props.posts.map(post => (
<div key={post.id} className="row">
<div className="container">
<h3>{post.title}</h3>
<p>{post.body}</p>
<button
onClick={() =>this.deletePost(post.id)}
className="btn btn-danger">
Delete
</button>
</div>
</div>
))
const divStyle = {
padding: '15px',
}
return (
<div style={divStyle}>
<PostForm />
<hr/>
{postItems}
</div>
)
}
}
const mapStateToProps = state => ({
posts: state.posts.items,
newPost: state.posts.item
})
export default connect(mapStateToProps, { fetchPosts, deletePost })(Post);
PostAction.js (Here is my delete action. I am using jsonplaceholder API post.)
export const deletePost = (postId) => dispatch => {
fetch('https://jsonplaceholder.typicode.com/posts/'+postId, {
method: 'DELETE',
})
.then(dispatch({
type: DELETE_POST,
payload: postId
}));
}
PostReducer.js (This is my reducer.)
case DELETE_POST:{
const newState = Object.assign([], state);`enter code here`
const filteredItems = newState.items.filter(items => {
return items.id != action.payload;
});
return filteredItems;
}

Answer 1

case DELETE_POST:{
const { items } = state;
const filteredItems = items.filter(items => {
return items.id != action.payload;
});
return {
...state,
items: [ ...filteredItems ]
};
}

Answer 2

Yes just replace
return filteredItems; to return { items: filteredItems }
But please can you check my code if it's correct. Thanks