you can use --include-shell to inclue a shell. but my recommendation is always keep a non-slimmed image somewhere so you can refer to it and some debugging can be done in either, also that allows you to use something like slim.ai's(company behind docker-slim) web based SaaS features which allow you to see the differences between 2 images and see the file system in nice web base file tree. some bugs may stem from removing what is necessary for app to work(sometimes caused by not loading a library during "slimming" process) for those types of errors you need to know how your app runs more then anything.
it a tradeoff