Catch VisRTX OpenGL interop exceptions on Optimus setups
@demarle Hey Dave, here's a brief patch to catch a crash which can happen on Optimus setups. When the OpenGL context is created on the integrated GPU, while OptiX is running on the dedicated GPU, interop will obviously fail.
In this case the VisRTX backend will automatically fall back to host-based framebuffer mapping.
(And I fixed a typo)
