Cleanup extension source code

[InAnYan]

1. Remove first empty line.
2. Remove unused things.
3. Add exceptions to spell checker.

Low-prio, this is just refactoring, and formalities.

Task with double points:

Setup prettifier (or how is this thing called) in the repo.

Ideally.... use TypeScript! (this is quadruple points)

[subhramit]

Setup prettifier (or how is this thing called) in the repo.

Ideally.... use TypeScript! (this is quadruple points)

Yes please.
Prettier and ESLint both.
Also use modern ES6+ syntax such as import over commonjs require