Error

[MohanaPriya2002]

I couldn't able to solve this issue
Object {
"locations": null,
"message": "Cannot return null for non-nullable type: 'User' within parent 'UserChatRoom' (/getUser/ChatRooms/items[2]/chatRoom/users/items[1]/user)",
"path": Array [
"getUser",
"ChatRooms",
"items",
2,
"chatRoom",
"users",
"items",
1,
"user",
],
},
],
}