Before the change access to non-existent `.cp312` attribute caused
irrecoverable eval failure:
$ nix build --no-link -f. python312Packages.array-data
...
error: attribute 'cp312' missing
After the change we use `throw` fallback to turn the error into
recoverable:
$ nix build --no-link -f. python312Packages.array-data
...
error: array-record is missing hash for cp312
The difference is visible when one tries to skip the derivations that
throw errors. Irrecoverable eval errors do not allow skipping such
derivations.
Sergei Trofimovich
836e74d695