Typescript: Option<> does not include null in generated types

[maiia-kuzmishyna]

Description

We are using typeshare to auto-translate Rust types into Typescript ones and facing issues with Option<> type.
Assume we have the following type:

#[typeshare]
struct MyStruct {
    my_name: Option<String>,
    my_age: u32,
}

The issue is that unless we are using #[serde(skip_serializing_if = "Option::is_none")] attribute, then if my_name has value None it gets serialized as null in JSON:

{
  "my_name": null,
  "my_age": 21
}

However, the generated Typescript definition does not reflect that my_name can hold a null value:

/*
 Generated by typeshare 1.13.2
*/

export interface MyStruct {
  my_name?: string;
  my_age: number;
}

This leads to potential unchecked nulls in our typescript part of the project.

Proposed solution

The best solution would be to adapt how Option<> types are treated based on the presence or absence of serde attribute.
If this is not possible, then null could simply be added to type definition of optional properties, enforcing safer typechecking.
However, that might be a breaking change to projects already relying on serde attribute so perhaps there should be a command line option to opt-in to this behavior.

Related issues

There is a similar issue about unit type: #43 which has been attempted to be fixed by #82 however reverted due to #96 and now is hanging in a draft pr #98.

Version

typeshare-cli version 1.13.2
typeshare crate version 1.0.4