e.g. selecting a track causes a ControlNotFoundException
if the ctrl surface is enabled, but no hardware is connected.
terminate called after throwing an instance of 'ArdourSurface::ControlNotFoundExceptio
```
#0 0x00007ffff14d8c2e in __cxa_throw () at /lib/x86_64-linux-gnu/libstdc++.so.6
#1 0x00007fffe2b560a0 in ArdourSurface::Console1::get_button(ArdourSurface::Console1::ControllerID) const (this=0x61d0017e1c80, id=ArdourSurface::Console1::FOCUS1)
at ../libs/surfaces/console1/console1.cc:928
#2 0x00007fffe2bfc647 in ArdourSurface::Console1::map_select() (this=0x61d0017e1c80) at ../libs/surfaces/console1/c1_operations.cc:653
#3 0x00007fffe2b55384 in ArdourSurface::Console1::map_stripable_state() (this=0x61d0017e1c80) at ../libs/surfaces/console1/console1.cc:832
#4 0x00007fffe2b541ab in ArdourSurface::Console1::set_current_stripable(std::shared_ptr<ARDOUR::Stripable>)
...
```
This does at least fix the crash. Ideally the surface would
only be enabled if there is hardware present.
