throw proper error when the docker image is not reachable

[mojtaba-esk]

When we set an image to the instance, k8s tries to download it and start the instance; however, if the image is not accessible or probably there are some other issues with it, it retries the process and keeps the instance pending, therefore, user does not know if the cluster is busy and has lack of resources or there is an issue with their setup e.g. image. This is an issue and it is suggested to throw an error if the image is corrupted or the instance cannot start with the given config.