Improve error reporting if kernel does not exist
Improve error reporting if kernel does not exist

GIO provides a very poor error message when enumerating files
for a directory which does not exist. Do an explicit check to
detect this scenario

Signed-off-by: Daniel P. Berrange <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

libvirt/libvirt-sandbox,erenyagdiran/libvirt-sandbox,agx/libvirt-sandbox-debian,libvirt/libvirt-sandbox,gczarcinski/libvirt-sandbox,gczarcinski/libvirt-sandbox,agx/libvirt-sandbox-debian,erenyagdiran/libvirt-sandbox,libvirt/libvirt-sandbox,agx/libvirt-sandbox-debian,gczarcinski/libvirt-sandbox,gczarcinski/libvirt-sandbox,agx/libvirt-sandbox-debian,agx/libvirt-sandbox-debian,erenyagdiran/libvirt-sandbox,erenyagdiran/libvirt-sandbox,gczarcinski/libvirt-sandbox,gczarcinski/libvirt-sandbox