Use TS typeguard for `utils/is` helpers

[CPatchane]

Hey 👋

In the utils/is file we have some helpers to check identities, but all functions just return boolean. What about using TS typeguard for that?

For example with the isError function:

export function isError(wat: any): boolean {...}
// become
export function isError(wat: any): wat is Error {...}

Then it will allow to do:

// myException type is: string | Error
if (!isError(myException)) {
  return event;
}
// previously we got the error: Property "name" doesn't exist on type string
const name = myException.name // no more need to cast to continue using it as an Error

What do you think?
This might be a big change internally (or not) since those are utils helpers and used everywhere but I could help if you need some PRs :)

[kamilogorek]

TIL: TypeScript has X is Y notation. Looks promising and useful! If you have some spare time, it'd be awesome if you can play around with it and see how much additional work it introduces :) Thanks!

[kamilogorek]

Closing the issue as a part of large repository cleanup, due to it being inactive and/or outdated.
Please do not hesitate to ping me if it is still relevant, and I will happily reopen and work on it.
Cheers!

[lobsterkatie]

I do think this is something we should do eventually, so I'm going to reopen this. I actually did one already, when I added isPrimitive. @CPatchane - Any interest in working on the rest? 🙂