Also looks like a false positive, but given that these were basically
testing for the `errdefs.Conflict` and `errdefs.NotFound` interfaces, I
replaced these with those;
daemon/stats/collector.go:154:6: type `notRunningErr` is unused (unused)
type notRunningErr interface {
^
daemon/stats/collector.go:159:6: type `notFoundErr` is unused (unused)
type notFoundErr interface {
^
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>