The error

The relation field [fieldname] must specify a `@relation` directive: `@relation(name: "MyRelation")`

Why you got this error

You have two fields that have the same value, for example:

user {
    id: ID
    name: String
    currentCompany: UserCompany
    previousCompany: UserCompany
}

This set of graphql query fields has two fields that have the value UserCompany. You have to either indicate a relation between user companies and users, or else create a subtype so they don’t reside at the same level.