The pkg/store errors are duplicated errors of NotFound and AlreadyExist from
containerd's errdefs package and thus do not properly serialize when running
errdefs.ToGRPC on them. CRI runs this function on every return from a CRI
method so the conversion fails if there is a cache miss from the store caches
for containers or sandboxes. This change verifies that the errors are properly
converted to their gRPC values.
Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>
