Have you seen this error?

building the system configuration...
error: flake 'git+file:///Users/matt/nixfiles' does not provide attribute 'packages.aarch64-darwin.darwinConfigurations.Bebop.system', 'legacyPackages.aarch64-darwin.darwinConfigurations.Bebop.system' or 'darwinConfigurations.Bebop.system'

I ran into this and it took me about a month before I realized that I had changed my hostname and that is why my nix flake was no longer building.

Background: I had some projects from school that I wanted to revisit and compile again, specifically a game called Worm. This was an assignment that needed to be linked against ncurses which isn’t installed out of the box on most machines. I’ve been dual booting NixOS for some time now on my gaming PC and I thought it was time to start using Nix Flakes with my own projects.