Added a check for an empty config to 'nakaz_utils'

src/nakaz_errors.erl

@@ -15,6 +15,8 @@ r({cant_execute_magic_fun, Mod}) ->
     %% FIXME(Dmitry): rename parsetransform to nakaz_pt
     {"Can't execute 'magic function' that must be generated "
      "by nakaz_pt in module ~s", [Mod]};
+r(empty) ->
+    {"Ooops, looks like the config is empty", []};
 r({malformed, [{app, {Name, _Body}}|_Rest]}) ->
     {"Malformed application structure in ~p, sections aren't mappings?",
      [Name]};

src/nakaz_internal.hrl

@@ -58,8 +58,8 @@
 -type untypical_readfile_errors() :: badarg
                                    | terminated.
 
--type config_structure_error() :: {malformed, [{section, atom()} |
-                                               {app, atom()}]}.
+-type config_structure_error() :: empty
+                                | {malformed, [{section | app, atom()}]}.
 
 -type proplist() :: [{any(), any()}].
 -type proplist(K, V) :: [{K, V}].

src/nakaz_utils.erl

@@ -5,6 +5,8 @@
 %% FIXME(Dmitry): spec
 -spec check_config_structure(raw_config()) -> {ok, raw_config()}
                                             | {error, config_structure_error()}.
+check_config_structure([]) ->
+    {error, empty};
 check_config_structure([{RawConfig, _pos}]) ->
     case check_config_apps(RawConfig) of
         [] -> {ok, RawConfig};