Weil ich hach einigen Versuchen nur per Zufall darauf gekommen bin - den Hinweis auf dieses Problem hatte ich so noch nirgendwo gefunden:
Q: I encountered a compilation error while executing RAILS_ENV=production bundle exec rails assets:precompile, but no more information is given. How to fix it?
A: Usually it's because your server ran out of memory while compiling assets. Use a swapfile or increase the swap space to increase the memory capacity. Run RAILS_ENV=production bundle exec rake tmp:cache:clear to clear cache, then execute RAILS_ENV=production bundle exec rails assets:precompile to compile again. Make sure you clear the cache after a compilation error, or it will show “Everything's OK” but leave the assets unchanged.
Die Lösung bei unserer Installation bestand allerdings darin, eine nodejs Version 16.x zu verwenden.