Invalid prop after save of device

Currently we get a warning about a problem in the handling of the patch request for updating an device.

[Vue warn]: Invalid prop: type check failed for prop "value". Expected Object, got String with value "204".

found in

---> <DeviceEditBasicPage> at pages/devices/_deviceId/basic/edit.vue
       <DeviceBasicPage> at pages/devices/_deviceId/basic.vue
         <VCard>
           <DevicePage> at pages/devices/_deviceId.vue
             <Nuxt>
               <VMain>
                 <VApp>
                   <Layouts/default.vue> at layouts/default.vue
                     <Root>

And:

TypeError: "someObject.contacts is undefined"
    createFromObject Device.ts:330
    onDeviceChanged edit.vue:152

It seems that there is an issue with the serializer, so that the old contacts entry is undefined (instead of just an empty array).