addons load relation throw error when the foreign key is null

[farshadfahimi]

I have simple query like below
let user: User | null = await order.related('user').query().debug(true).first()

some times the usersId is null in my query and the above query on execute got below error
Cannot preload \"user\", value of \"Order.usersId\" is undefined

I think it's not a good Idea to thorw an error it's better to return null

[thetutlage]

You can simply avoid running the query by checking for the userId beforehand.

let user: User | null = order.userId ? await order.related('user').query().debug(true).first() : null