Default sluggification is simplistic, relying on a title field and performing no inference whatsoever.

With no field named "title", entries currently fail to save.

The ideal fix is to simply make slugs editable in the editor UI.

Considerations:

• Slug editing can be switched off through config
• If slug editing is switched off, each collection config must be validated on CMS load to ensure a slug can be derived
• Prepopulate with the same best guess or configured slug template result that we currently use
• Only valid characters may be entered in the slug field
• Slugs and filenames are not always the same, so it should be possible to provide them separately somehow (see comment below for example)