module definition error provenance

[blaggacao]

A definition for option `outputs./' is not of type `package'. Definition values:
- In `/nix/store/nj2n...-source/src/evaluator/modules/default.nix'

This error message says just about nothing. We need to improve it, possibly by using _file module attribute.

[blaggacao]

this isn't as trivial as I initially thougt

[kamadorueda]

I just discovered this perl:

nix-repl> builtins.unsafeGetAttrPos "a" { a = "123";}
{ column = 33; file = "(string)"; line = 1; }