When the ECR stack was not upserted during the build phase, mu will attempt to upsert it during the deploy phase. This can cause potentially confusing behavior, such as mu being unable to create the ECR stack because the IAM roles created previously don't have the necessary permissions. This behavior can be triggered by building a pipeline with the ecs provider that does not have a Dockerfile, since the presence of a Dockerfile is what triggers the creation of the ECS/ECR resources during the build phase.

If there's no valid reason mu should attempt to upsert the ECR stack during mu svc deploy, a potential improvement might be to have it only attempt to resolve the image from ECR and throw an error if it doesn't exist without attempting to create the stack.