order by with multiple aggregate fields throws error

Making a query with 2 aggregate fields in order_by that use min/max and different relations causes an SQL error.
```graphql
{
  author (order_by: [{
    articles_aggregate: {
        min: {
            title: asc
        }
    }
  }, {
    posts_aggregate: {
        max: {
           text: asc
        }
    }
  }]) {
    id
    name
    articles {
        id
    }
  }
```