top-level/aliases: abort evaluation on check error

The `aliases.nix` file is full of "expected errors", which the CI check
for "does nixpkgs with aliases eval?" *must* ignore. However, this also
hides an unexpected error, the check which prevents shadowing of
existing attributes in all-packages.nix.

By elevating this check to use `abort`, this will break the CI check for
sure.

Author: wolfgangwalther

pkgs/top-level/aliases.nix

@@ -208,7 +208,7 @@ let
   # Make sure that we are not shadowing something from all-packages.nix.
   checkInPkgs =
     n: alias:
-    if builtins.hasAttr n super then throw "Alias ${n} is still in all-packages.nix" else alias;
+    if builtins.hasAttr n super then abort "Alias ${n} is still in all-packages.nix" else alias;
 
   mapAliases =
     aliases: lib.mapAttrs (n: alias: removeRecurseForDerivations (checkInPkgs n alias)) aliases;