now gitty responds properly when path is not found

src/git_repo.erl

@@ -26,7 +26,17 @@
 }).
 
 init(Path) when is_list(Path) ->
-  #git{path = Path};
+  case file:read_file_info(filename:join(Path, "objects")) of
+    {ok, _} ->
+      #git{path = Path};
+    {error, _} ->
+      case file:read_file_info(filename:join(Path, ".git/objects")) of
+        {ok, _} ->
+          #git{path = filename:join(Path, ".git")};
+        {error, _} ->
+          error({invalid_git_repo_path,Path})
+      end
+  end;
 
 init(#git{} = Git) ->
   Git.

src/gitty.erl

@@ -15,25 +15,25 @@ show(Git, Path) when is_list(Path) ->
 show(Git, Path) when is_list(Git) ->
   show(git_repo:init(Git), Path);
 
-show(Git, Path) ->
+show(Git, Path) when is_tuple(Git) andalso is_binary(Path) ->
   case re:run(Path, ":") of
     {match, _} -> show_file_by_path(Git, Path);
     nomatch when size(Path) == 40 -> git_repo:read_object(Git, Path);
     _ -> show_file_by_path(Git, Path)
   end.
 
-show_file_by_path(Git, RawPath) ->
+show_file_by_path(Git, RawPath) when is_tuple(Git) andalso is_binary(RawPath) ->
   {ok, Git1, Tree, Path} = prepare_path(git_repo:init(Git), RawPath),
 
-  {ok, Git2, Type, Blob} = case Path of
+  Reply = case Path of
     <<>> -> 
       {ok, Git1, tree, Tree} ;
     _ ->
       Parts = binary:split(Path, <<"/">>, [global]),
       lookup(Git1, Parts, Tree)
   end,
 
-  {ok, Git2, Type, Blob}.
+  Reply.
 
 
 
@@ -91,6 +91,7 @@ prepare_path(Git, Path) when is_binary(Path) ->
     [Path_] ->
       {proplists:get_value(<<"master">>, Refs), Path_}
   end,
+  is_binary(SHA1) orelse error({cant_find_master_for,Path}),
   {ok, Git2, commit, Head} = git_repo:read_object(Git1, SHA1),
   {ok, Git3, tree, Tree} = git_repo:read_object(Git2, proplists:get_value(tree, Head)),
   {ok, Git3, Tree, RealPath}.
@@ -151,6 +152,9 @@ show1_test() ->
   ?assertMatch({ok, _, blob, _}, show(fixture("dot_git"), "README.txt")),
   ok.
 
+not_existent_test() ->
+  ?assertEqual({error, enoent}, gitty:show(fixture("small_git"), "ru/non_existent.html")).
+
 list_test() ->
   ?assertMatch({ok, _, [
     {<<"README">>, <<"100644">>,<<"cd0d7186badd8fcfbfbdf35a0b9f2c8aaf465e77">>},