Crash when resizing openconsole to 0 rows (was: std::clamping the cursor, 2023 edition)

[zadjii-msft]

@zadjii-msft I think we may want to reopen this issue. I was just testing PR #14661, which kind of reverts your fix for this, and I wanted to make sure I hadn't reintroduced the bug. What I discovered was that the issue was never fully resolved - while we don't get a clamp assertion in the cursor code, we now just get it somewhere else instead! For me it occurred here:

terminal/src/terminal/adapter/adaptDispatch.cpp

Line 219 in 4d27a05

row = std::clamp(row + rowOffset.Value, viewport.top, viewport.bottom - 1);

And I double checked with the commit from when PR #13001 was merged (7990436), and it was already failing then. It may not be obvious in some shells, but in a WSL bash shell it crashes straight away. In a cmd shell I had to type some command (e.g. CLS) while the window had a zero size in order to trigger the crash.

It's not a major problem, since it only happens in a debug build, but if we think it needs fixing we should probably reopen this, or at least open another issue if you prefer that.

As for how we fix it, I would have liked it if we could put a minimum size on the viewport, but I suspect that's not possible in conhost for legacy reasons. So failing that, a quick fix would be to replace the clamp calls with a min/max combo which won't assert. But my concern is that the VT architecture is kind of dependent on a non-zero screen size, so there's a fair chance this issue might just surface elsewhere at some point in the future. Maybe we just have to accept that.

Originally posted by @j4james in #12917 (comment)