Replace defensive clear with assert in createImageViews

[asuessenbach]

I don't see, how swapChainImageViews could be not empty in createImageViews(). Do I miss something?

In any case, I would replace the defensive clear() with an assert, to make clear it's a prerequisite for this function.

[SaschaWillems]

Does make sense in this chapter. For msvc this needs to include assert though.

Looking at other chapters, the createImageViews function needs some fix ups in other chapters too. In some of the chapters (e.g. 23) it just emplaces back with no clear, so every resize will just add new image views.

[asuessenbach]

Asserting on empty swapChainImageViews in createImageViews() in all chapters.

Chapters supporting resizing already clear the swapChainImageViews in cleanupSwapChain()

Besides that, all chapters staring with 17_swap_chain_recreation are crashing on resize.

[SaschaWillems]

Thanks 👍🏻

Crash on resize will be fixed in #85

We should merge that as soon as possible