Interview question of the issue #306 of rendezvous with cassidoo.
Write a function that takes an array of consecutive, increasing letters as input, and returns any missing letters in the array between the first and last letter.
Example:
> missingLetters(['a','b','c','d','f'])
> ['e']
> missingLetters(['a','b','c','d','e','h','i','j','k','l','m','n','o','p','q','r','s','t','u','w','x','y','z'])
> ['f','g','v']Just pnpm i to install all dependencies and then pnpm t to run the tests!