https://eloquentjavascript.net/08_error.html#i_iGlwnUbkRs

Eloquent JavaScript 0802 The locked box.js

const box = {
  locked: true,
  unlock() { this.locked = false; },
  lock() { this.locked = true;  },
  _content: [],
  get content() {
    if (this.locked) throw new Error("Locked!");
    return this._content;
  }
};

function withBoxUnlocked(body) {
  // Your code here.
  let locked = false;
  if (box.locked) {
    locked = true;
  	box.unlock();
  }
  try {
    body();
  } finally {
    if (locked) {
      box.lock();
    }
  }
}

withBoxUnlocked(function() {
  box.content.push("gold piece");
});

try {
  withBoxUnlocked(function() {
    throw new Error("Pirates on the horizon! Abort!");
  });
} catch (e) {
  console.log("Error raised: " + e);
}
console.log(box.locked);
// → true
box.unlock();
console.log(box.content);
// -> ["gold piece"]