Also note index in record_element

I changed it from noting the index to just noting the field name, but
actually both pieces of information are important, since if there was
a type error, presumably the type information is actually wrong.

Now we put the index first, since that is the part of the FATE tuple
that failed, and then the field name that that would be if the type
information were correct, in case that is useful.

src/hz_aaci.erl

@@ -832,7 +832,7 @@ coerce_record_to_map(O, N, MemberTypes, Tuple) ->
 correct_record_error_paths(Names, Errors) ->
     CorrectOne = fun({Error, [{record_element, N} | Path]}) ->
                      FieldName = lists:nth(N + 1, Names),
-                     {Error, [{record_element, FieldName} | Path]}
+                     {Error, [{record_element, N, FieldName} | Path]}
                  end,
     Corrected = lists:map(CorrectOne, Errors),
     {error, Corrected}.
@@ -1169,7 +1169,7 @@ singleton_record_substitution_test() ->
     check_roundtrip(HOutput, #{"it" => {123, 456}}, {tuple, {123, 456}}),
     % Also check that records have accurate paths, since the implementation for
     % record error paths is a bit fiddly.
-    {error, [{{tuple_too_many_terms, _, _, _}, [{record_element, "it"}]}]} = fate_to_erlang(HOutput, {tuple, {1, 2, 3}}).
+    {error, [{{tuple_too_many_terms, _, _, _}, [{record_element, 0, "it"}]}]} = fate_to_erlang(HOutput, {tuple, {1, 2, 3}}).
 
 tuple_substitution_test() ->
     Contract = "