Consider limiting input type to string

[harveysanders]

Description

The type for parameter input in normalizeSync implies that undefined and null are acceptable inputs. However, the first line of the function throws an error if the input is not a string.

https://github.com/motss/normalize-diacritics/blob/main/src/normalize-sync.ts#L3-L6

I believe it would be more ergonomic to have TypeScript signal to the dev that only strings are acceptable.
In my opinion, TS is best suited to help devs avoid runtime errors by attempting to move common issues to compile-time errors. With this in mind, I think it would be more helpful to set input to only string.

export function normalizeSync(input: string): string {
  //....
}

That way we get type errors before running the code:

/** @type {string | undefined | null} */
const input = getInputFromWherever();

normalizeSync(input);
              ^^^^
              // Argument of type 'string | null | undefined' 
              // is not assignable to parameter of type 'string'.
              // Type 'undefined' is not assignable to type 'string'.ts(2345)

What do you think?

Anyway, thanks for building this lib 🙂

[harveysanders]

If you agree, I'm happy to submit a PR : )

[motss]

@harveysanders Thanks for the feedback. I initially included null and undefined because of JavaScript being a dynamic language. I really like your explanation that TypeScript should tell the users the correct type and totally agree with your points.

Please help raise a PR to fix this.

[harveysanders]

@motss thanks for the quick response. Sounds good! I'll try to get one in next week : )

[harveysanders]

@motss I've just submitted a PR