index out of bounds errors are handled in separate ways depending on the kind of array you are using. If I understand how it works correctly, you can be working with one of three main kinds of arrays: slices with a known length, slices with an unknown length, or a growable vector. In the case of slices with a known length, ie: let a = [0]; then trying to say a[1] is a compile error since the compiler knows the length of the array at compile time, it will not let this code compile. In the case of an unknown length at compile time, the compiler cannot really help you here, but it will cause a task failure when you try to access out of bounds (since it does know the length at runtime, it checks to make sure that it is in bounds). This is similar to what happens when you are trying to access an element that doesn't exist on growable vector as well. I hope this information clears up somethings for you and even more so I hope my information is correct! I'm still learning rust, so I still have misunderstandings quite often.