Crash if camera is already open

[navzam]

If the camera is being used by another source, camera_open() usually crashes the user program.

[Zacharyprime]

This is confirmed to be an issue on the Wombat.
The program will return with NULL instead of 0 and crash if the camera is open in Botui.

[EugeneDMyers]

Actually, the 0 return is normal (and expected behavior) when the camera cannot be opened. The user program should check to see if there is a 0 return when the camera cannot be opened because BOTUI has control of the camera.

A crash can be prevented by camera::Device::update (camera.cpp) check to see if the camera is opened by calling camera::Device::isOpen(). That is a best a bandaid solution as the code in camera.cpp is a hodgpodge of support for non-opencv and opencv cameras.

[EugeneDMyers]

Also, in this case the user program will loop waiting for a frame to appear. They still need to check for this case.