No friendly message when adding item to project in non-existing language

Description

1. Make sure English and Swedish are both enabled for the site.
2. Create a new project and switch site to Swedish.
3. Try to drag and drop an Alloy Page (English version) to the project

Expected: Message shows "The item you are trying to add does not exist in the language you are currently editing:

Actual: Message shows: "Unable to load /release-9-5-0-alloy/EPiServer/cms/Stores/project-item/ status: 403"

Note: No such issue for CMS.UI.9.4.4 and lower