refactor: add a more specific type for no container info error

Author: Jeremy L. Morris

pkg/container/container.go

@@ -285,7 +285,7 @@ func (c Container) VerifyConfiguration() error {
 
 	containerInfo := c.ContainerInfo()
 	if containerInfo == nil {
-		return errorInvalidConfig
+		return errorNoContainerInfo
 	}
 
 	containerConfig := containerInfo.Config

pkg/container/container_test.go

@@ -23,7 +23,7 @@ var _ = Describe("the container", func() {
 				c := mockContainerWithPortBindings()
 				c.containerInfo = nil
 				err := c.VerifyConfiguration()
-				Expect(err).To(Equal(errorInvalidConfig))
+				Expect(err).To(Equal(errorNoContainerInfo))
 			})
 		})
 		When("verifying a container with no config", func() {

pkg/container/errors.go

@@ -3,5 +3,6 @@ package container
 import "errors"
 
 var errorNoImageInfo = errors.New("no available image info")
+var errorNoContainerInfo = errors.New("no available container info")
 var errorNoExposedPorts = errors.New("exposed ports does not match port bindings")
 var errorInvalidConfig = errors.New("container configuration missing or invalid")