fix(ds): make dialyzer happy

apps/emqx_durable_storage/src/emqx_ds_app.erl

@@ -4,6 +4,8 @@
 
 -module(emqx_ds_app).
 
+-dialyzer({nowarn_function, storage/0}).
+
 -export([start/2]).
 
 -include("emqx_ds_int.hrl").
@@ -14,20 +16,21 @@ start(_Type, _Args) ->
 
 init_mnesia() ->
     %% FIXME: This is a temporary workaround to avoid crashes when starting on Windows
-    Storage =
-        case mria:rocksdb_backend_available() of
-            true ->
-                rocksdb_copies;
-            _ ->
-                disc_copies
-        end,
     ok = mria:create_table(
         ?SESSION_TAB,
         [
             {rlog_shard, ?DS_SHARD},
             {type, set},
-            {storage, Storage},
+            {storage, storage()},
             {record_name, session},
             {attributes, record_info(fields, session)}
         ]
     ).
+
+storage() ->
+    case mria:rocksdb_backend_available() of
+        true ->
+            rocksdb_copies;
+        _ ->
+            disc_copies
+    end.