Handling API errors on nested (hasMany) models

I have a freight order model with a hasMany relation with a shipment model. I do a save on the freight order, and send all data in one go. I can handle errors on the freight order model just fine, but can not figure out how to handle API errors on nested models in the template.

The freight order model:

import DS from 'ember-data';

export default DS.Model.extend({
    comment: DS.attr('string'),
    freighter: DS.belongsTo('account'),
    shipments: DS.hasMany('shipment', { inverse: null })
});

The shipment model:

import DS from 'ember-data';

export default DS.Model.extend({
  pickup_address: DS.belongsTo('address', { inverse: null }),
  delivery_address: DS.belongsTo('address', { inverse: null }),
  shipment_lines: DS.hasMany('shipment-line', { inverse: null }),
  shipmentPrice: Ember.computed('shipment_lines.@each.package_price', function () {
    let price = 0;
    this.get('shipment_lines').forEach(function(shipment_line) {
      price += Number(shipment_line.get('package_price'));
    });
    return price;
  }),
});

Errors directly on the freight order I handle in the handlebars template like this:

    <div class="errorMessage">
        
    </div>

Thank you for your time.