if (!arrayToCheck || !Array.isArray(arrayToCheck)) {
    throw new TypeError('Array expected but ' +
      typeof arrayToCheck + ' found.');
}

if (!Array.isArray(arrayToCheck)) {
    throw new TypeError(`Array expected but ${typeof arrayToCheck} found.`);
}

return arrayToCheck.filter((e, i, arr) => i === arr.indexOf(e));

function removeDuplicates(array) {
  'use strict';
  if (!Array.isArray(array))
    throw new TypeError(`Array expected but ${typeof array} found.`);
  return array.filter((e, i, arr) => i === arr.indexOf(e));
}