There is such a button, and its usually labeled "Restart Computer"
I think reaper has built in protection for when the interface driver crashes, or isn't connected... Reaper simply disconnects, and doesn't crash with it.
In my experience, almost all other daws will instantly crash hard if you do this.
Launching reaper without the interface connected (esp USB1 or USB2) seems to invoke reaper to ignore it ... and the only fix is a hard reboot.