Rule suggestion: unnecessary-else

[JoshuaKGoldberg]

Rule Suggestion

Is your rule for a general problem or is it specific to your development style?

General problem

What does your suggested rule do?

If an if block contains a return, throw, continue or break statement, the else block becomes unnecessary. Its contents can be placed outside of the block.

List several examples where your rule could be used

Instead of:

if (foo) {
    throw new Error();
} else {
    // ...
}

Prefer:

if (foo) {
    throw new Error();
}

// ...

See https://github.com/ajafff/tslint-consistent-codestyle/blob/master/docs/no-unnecessary-else.md

Additional context

Spinning off of #2040: moving some rules of tslint-consistent-codestyle to tslint core.
Note that as ajafff mentioned, copied code without substantial changes needs to retain the original license.

[debsmita1]

I am working on this at the moment. Do let me know if there is something that I should keep in mind. :)

[debsmita1]

@JoshuaKGoldberg Could you kindly review this PR and tell me where am I going wrong ? :)