Please make user object optional

[makowskid]

Package is actually useless if I can't create generic short URLs, only user-specific.

[nasrulhazim]

Package is actually useless if I can't create generic short URLs, only user-specific.

the intention of the package to have shortened url, own by user. it never meant for guest at the first place. This is, i believe similar to bit.ly.

if you require null user's id, you always can update the migration when publish to nullable.