events.js:288. :Cannot read property 'items' of null - node.js

Question

I have tried restarting the server multiple times. I also removed the node modules and installed it again. I also cleared the cache and also restarted VS code many time. Nothing seems to be working. Now after writing foundList.items.push(item); i cannot add items to my route directory as well. Before this i was able to add or delete items from the route directory. Can anyone please help me with this?
Here is my code for Express:
app.post("/", function (req, res) {
const itemName = req.body.newItem;
const listName = req.body.list;
const item = new Item({
name: itemName,
});
//Check id the user tried to add the list is default list or the custom list. Then find the custom list and add the new item and redirect to the custom list i.e ///listName
if (listName === "Today") {
item.save();
res.redirect("/");
} else {
List.findOne({ name: listName }, function (err, foundList) {
foundList.items.push(item);
foundList.save();
res.redirect("/" + listName);
});
}
});
Here is my EJS code as well.
<div class="box heading">
<h1><%= listTitle %></h1>
</div>
<div class="box">
<% newListItems.forEach(function(item) { %>
<form action="/delete" method="POST">
<div class="item">
<input
type="checkbox"
name="checkbox"
value="<%= item._id %>"
onChange="this.form.submit()"
/>
<p><%=item.name%></p>
</div>
</form>
<%});%>
<form class="item" action="/" method="post">
<input
type="text"
placeholder="newItem"
name="newItem"
autocomplete="off"
/>
<button type="submit" name="button" value="<%= listTitle %>">+</button>
</form>
</div>

Answer 1

It looks like my Udemy training course I am doing. I am pretty new to coding and have spent couple of hours trying to fix the same code. Anyways:
try to change the line: foundList.items.push(item); to singular: foundList.item.push(item); I can't see your listSchema in the code. Check it and see if you have "item" or "items".
const listSchema = {
name: String,
item: [itemsSchema]
};
I had item declared in the schema but was calling items in "foundList.items.push(item), and the server was crushing all the times.

Answer 2

It is landing into error as listName case is not matching with the list items available. require and install lodash and try using:
const listName= _.lowerCase(req.body.list);