If a command buffer fails in Metal, its `status` becomes
`MTLCommandBufferStatusError`, and its `error` property is populated. In
Vulkan, command buffer failure usually triggers device loss. This is
because most drivers can't guarantee that resources weren't affected in
an undefined fashion. We can't make that guarantee, either, so when a
Metal command buffer has an error, mark the device lost. The error is
also logged. All waits are immediately signaled; those that were client
requests instead of internal implementation details immediately return
`VK_ERROR_DEVICE_LOST`.
The app may be able to recreate the logical device and reconstruct its
state. However, some Metal errors are severe enough that all subsequent
command buffers will fail--in those cases, the physical device becomes
lost as well, indicating that the device cannot be recreated.
Only certain commands are allowed to report device loss. These commands
test for device loss before continuing, and will immediately return if
the device is lost.
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