error message formatting

src/libexpr/eval.cc

@@ -1366,6 +1366,7 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
                 actualArgs->attrs->push_back(*j);
             } else if (!i.def) {
                 throwUndefinedVarError(i.pos, R"(cannot auto-call a function that has an argument without a default value ('%1%')
+
 An 'auto-call' is when a nix expression is evaluated without any external arguments.
 If that nix expression is a function, and that function's arguments all have default
 values, then all is well.
@@ -1387,7 +1388,7 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
     nixpkgs.stdenv.mkDerivation {
   ...
 
-  See this nix pill for more information re callPackage format:
+More about callPackage: 
 https://nixos.org/guides/nix-pills/callpackage-design-pattern.html)", i.name);
             }
         }