Relay nodeDefinition throws "Right-hand side of 'instanceof' is not callable" - graphql

Question

I am learning GraphQL and have just started implementing graphql-relay on my node server in the past couple days. When declaring my Relay node definitions I am getting the error "Right-hand side of 'instanceof' is not callable", where the right-hand side is an object with a constructor function. As far as I can tell this is not due to improper usage, also considering this is copied from the docs. I am not sure what the expected outcome is when it is properly working, I assume it returns the GraphQL type to be put through the works and have the requested data returned.
var {nodeInterface, nodeField} = nodeDefinitions(
(globalId) => {
var {type, id} = fromGlobalId(globalId);
console.log(type);
if (type === 'User') {
return db.models.user.findById(id)
} else if (type === 'Video') {
return db.models.video.findById(id)
}
else if (type === 'Producer') {
return db.models.user.findById(id)
}
else if (type === 'Viewer') {
return db.models.user.findById(id)
}else {
return null;
}
},
(obj) => {
console.log(obj); // Sequelize object
console.log(User); // user
console.log(User.constructor); // valid constructor
// This is where the error occurs
if (obj instanceof User) {
return UserType;
} else if (obj instanceof Video) {
return VideoType;
} else {
return null;
}
});
Notes:
Using Sequelize ORM.
User is an Interface in GraphQL the schema implemented by Viewer, Producer, and GeneralUser types. My psql database on the otherhand has one User table which is why the second function only checks for User and not these additional types.
All my other queries for users, videos, etc. work fine, it is only when searching by node && globalId when it breaks

Answer 1

An "object with a constructor function" isn't callable. Probably you need to make that object a class with a constructor like this:
class User {
constructor(id, name, email) {
this.id = id;
// etc
}
}

Answer 2

You need to change the code from:
...
if (obj instanceof User) {
...
} else if (obj instanceof Video) {
....
to:
...
if (obj instanceof User.Instance) {
...
} else if (obj instanceof Video.Instance) {
....