I’m sorry but your problem here is solely with JavaScript, not TypeScript. TS is right to assign that type to the value, because that is perfectly valid JS, and that is the type you should expect.
It’s not hard to check for undefined
and there are absolutely times you wouldn’t want an error to be thrown, so this is just you having a preference, and judging an entire language based on your preference.
There are actual reasons to dislike how JS works, out of bounds array access returning undefined is not one of them.
To add to my own comment, I want to remind you that JavaScript was designed to power websites, and having an entire website break because an array didn’t have anything in it yet is probably worse than the alternative.
A lot of JS’ decisions actually make sense when you understand its history. That doesn’t mean it’s a great language, but it’s undeniably good at fulfilling its original purpose, making websites interactive in myriad different browser implementations.