The opacity of Nix errors is largely (entirely?) constrained to the module systems (notably NixOS, Nix-Darwin, and Home Manager). (This is unfortunate, because these are actually some of the best parts of the Nix ecosystem.)
The issue is essentially that configuration options all get merged into a global namespace, but there are no facilities to track where they came from. So when configuration mismatches of certain kinds occur, you get an error in some library code that's trying to merge or coerce two incompatible values, and nothing pointing you to the two places where the conflicting values are originally set.
(This kind of error, the most common mostly-useless error message, is typically easily debugged by searching for the relevant options in your configuration and in the source code of that collection of modules. But that is still backwards and a chore, and deserves a real solution.)
Anyway, the package definitions and builds in Nixpkgs don't use any such module system in any way. So this tool is not wrapping the functionality that is associated with opaque error messages. :)
The issue is essentially that configuration options all get merged into a global namespace, but there are no facilities to track where they came from. So when configuration mismatches of certain kinds occur, you get an error in some library code that's trying to merge or coerce two incompatible values, and nothing pointing you to the two places where the conflicting values are originally set.
(This kind of error, the most common mostly-useless error message, is typically easily debugged by searching for the relevant options in your configuration and in the source code of that collection of modules. But that is still backwards and a chore, and deserves a real solution.)
Anyway, the package definitions and builds in Nixpkgs don't use any such module system in any way. So this tool is not wrapping the functionality that is associated with opaque error messages. :)