/// Errors a `D3d12FrameRenderer`/`D3d11FrameRenderer` implementation can
/// report. GPU-vendor-agnostic (no D3D11/D3D12-specific type in here), so
/// it's shared by both instead of each defining its own copy — and left
/// ungated (not behind either renderer feature) so it's a stable type to
/// reference regardless of which one a caller actually enables.