Display a dialog when the user selects an invalid font

[matt2405warner]

Summary of the new feature/enhancement

Currently when changing the 'fontFace' to a font that doesn't exist the font size just gets so small (~0.5 font size) that you can't read the text.

Proposed technical implementation details (optional)

It would be nice if the terminal informed the user that the font is not valid - Maybe a pop-up/modal?

[metathinker]

I also see an earlier report (#550) that Terminal would actually crash when a profile referred to a nonexistent font name. Is that not happening anymore? Perhaps that problem was partially fixed, resulting in what you see.

[matt2405warner]

I haven't had it crash on me yet when I change the font to an invalid one. It just makes the font extremely small.

[zadjii-msft]

Well this is definitely relevant to #610, @miniksa might be interested in knowing that. I was certainly under the impression we'd crash when the font wasn't found.

[miniksa]

I mean, literally anyone who isn't me can go F5 the thing in Visual Studio setting a breakpoint in dxrenderer.cpp where it hands your font preference into DirectWrite's layout and see what it comes back with to reason out why this is. I think it's GetProposedFont method.

But if no one else does that, I'll get to this eventually.

[metathinker]

Well, for what it's worth, I can't reproduce this problem. I gave a profile a nonexistent font name and Terminal crashed as per #550 when creating a tab with that profile; it didn't show a tab with tiny text as you report here.