Problems with the debugger empty state page

[elliette]

The empty state page (see image below) shows up when selecting a file fails. When that happens, no keyboard shortcuts work, so opening with command+P (as the empty state suggests) doesn't work.

We should:

1. Add a button to the empty state that will trigger the file opener (this can be a stop gap until we fix 2 below)
2. Figure out why the empty state shows up in the first place and why keyboard shortcuts don't work.

Unfortunately the empty state page only shows up sporadically so it's hard to reproduce.

[elliette]

I've discovered that the keyboard shortcuts also don't work in the non-empty state if another widget claims focus (eg below clicking the console causes the focus to be lost):