Too many unspecific “invalid label” errors when adding books

[nclm]

When scanning barcodes for books that are not yet in the database, Inventaire lets you add the title (either creating a new work or linking an existing work), which is great. However, more often than not, it leads to a unclear “invalid label” error after clicking on “Create selected books”. As a user, it is unclear what is wrong and what should I do and how to actually add the books then.

Example:

[maxlath]

Thanks for reporting. This should now have been fixed by 898ce1e, please re-open if that's not the case.