Fix Dialyzer warning and slightly reformat code

src/rebar_lfe_compiler.erl

@@ -64,11 +64,15 @@ compile_lfe(Source, Target, Config) ->
             Opts = [{i, "include"}, {outdir, "ebin"}, report, return] ++
                 rebar_config:get_list(Config, erl_opts, []),
             case lfe_comp:file(Source, Opts) of
-                {ok, _, []} -> ok;
+                {ok, _, []} ->
+                    ok;
                 {ok, _, _Warnings} ->
                     case lists:member(fail_on_warning, Opts) of
-                        true -> file:delete(Target), ?FAIL;
-                        false -> ok
+                        true ->
+                            ok = file:delete(Target),
+                            ?FAIL;
+                        false ->
+                            ok
                     end;
                 _ -> ?FAIL
             end