问迭代对象的值会产生未定义的结果

EN

for (const iq of Object.values(iqByName)) {
  if (iq === undefined) throw new Error("IQ undefined.");
  const iq2 = 2 * iq; // Object is possibly 'undefined'
  console.log(iq2);
}

type IQByName = Partial<Record<string, number>>;
const iqByName: IQByName = { Trump: 185 };

for (const iqKey of  Object.keys(iqByName)) {
    const iq2 = 2 * iqByName[iqKey];
    console.log(iq2);
}