I don't understand this

Line 62 of this commit's flake.nix should bail with an attribute-missing
error while evaluating `buildDerivations.releases`, at the point where
Nix tries to inherit two variables from an empty `clusterData`.

...Or is it that I will have problems when I add something using
lib.builders.helmChart to `./system`? I'll only find out tomorrow.

lib/flake-builders.nix

@@ -42,6 +42,13 @@ in {
 
               # Values understood by lib.builders.helmChart
               # and ignored by the rest.
+              # COMBAK: How in the world does this work when
+              # clusterData is empty, as it is when building
+              # the flake's `systemReleases`?
+              # When I do this in a REPL:
+              # > foo={a=1;}
+              # > {inherit(foo)b;}
+              # ... I get an attribute-missing error.
               inherit (clusterData) kubeVersion apiVersions;
             })
         # By injecting `name` and `namespace` here, I remove