Change generic types

[Unaxe]

A good practice is to don't use generic type for the infos like Email, phone number...
I recommand to create an email type instead of the string | null type to avoid DataBase corruptions and any others problems

[Arno500]

It's a bit more complicated than that. Databases rarely support “rich” strings (like “emails”) and it's not their job to perform validation on them. Magically adding TypeScript types won't make the data “safe” nor perform any type of validation.
The embedded system SHOULD, however, support this kind of validation, but this is usually a system decoupled from the typing system.