Have you tried
./launcher start app
Though if you did a ./launcher cleanup while the old container was down and don’t have a container to start then you are in something of a pickle. Is that what you did? It looks like what you did.
I think that it’s a bug that a bad theme component would make it impossible to upgrade, so perhaps a solution will be forthcoming.
I think you could modify the database to remove the theme component, but if you don’t have a container running to let you access the database, I’m not quite sure how you’d do that.
My only other emergency ASAP solution would be to see if you could restore the existing database on a clean installation.
Perhaps you can restore the database to a clean install (maybe it’ll ignore the broken theme?), then delete your database and rebuild a new empty database with upgraded discourse, then restore the database from the remote clean installation.
Another solution would be to create a database-only image and use SQL to remove the broken theme component.