Add an analogous method to `.required()` for `.nullish()` (Feature request)

[aantia]

Feature Request

Add a method that will strip .nullish() off all properties, similar to how .required() strips .optional() off all properties.

Use Case

In my Zod schemas I have to use .nullish() extensively - essentially we have to support a null value for anything that might also be undefined or simply not present.

This works very well for us, but there is one particular part of the code where we need stricter validation of a particular object. If we were using .optional() we could simply add .required() onto the schema, but as we instead want to strip off .nullish() we do a much less pleasant:

const DerivedSchema = z.strictObject({
  ...BaseSchema.shape,
  propertyName: BaseSchema.shape.propertyName.unwrap().unwrap(),
// etc
}).required();

It would obviously be much nicer-looking if we just did a new schema, but to keep the logic clear and to keep it DRY we prefer to extend the original one.

Something like this would be ideal:

const DerivedSchema = z.strictObject({
  ...BaseSchema.shape
}).notNullish();