I'm on a multiplayer server. The Minecraft client crashed just as I was trying to craft some dyed wool. I had ink sacs and white wool in my inventory and I shift-clicked on the black wool entry in the new crafting interface. That is when the client crashed.

I went looking for the launcher window, because that usually pops up with a crash report, but I couldn't find the window. It turned out that it had popped up on another desktop (I have multiple desktops enabled), but it doesn't show up on the dock, and it doesn't appear in the list when I press Command-Tab.

When I click "Show more details," it shows me this:
The game crashed whilst unexpected error
Error: java.lang.NullPointerException: Unexpected error

I had to type this in manually, because selecting the text and pressing Command-C just gives me an error sound, and "Copy to clipboard" is not clickable.

Even worse, "View crash report" is also not clickable. I did find the crash report under ~/Library/Application Support/crash-reports, and I will file that as a separate bug.