handling of optional fields / lack of field value

[mixvar]

current solution:

• fields.number() corresponds to type number | "" to represent empty input value as ""
• fields.date() corresponds to type Date | null to represent lack of date
• fields.choice() can accept "" to represent empty select input
• other fields do not have dedicated type representing lack of value

this can be confusing and require additional casting of form state to domain models on submit.
research better solution