fix: swagger doc 500 crash

apps/emqx_conf/src/emqx_conf.erl

@@ -162,7 +162,7 @@ gen_schema_json(Dir, I18nFile, SchemaModule, Lang) ->
     ok = file:write_file(SchemaJsonFile, IoData).
 
 gen_api_schema_json(Dir, I18nFile, Lang) ->
-    emqx_dashboard:init_i18n(I18nFile, Lang),
+    emqx_dashboard:init_i18n(I18nFile, list_to_binary(Lang)),
     gen_api_schema_json_hotconf(Dir, Lang),
     gen_api_schema_json_bridge(Dir, Lang),
     emqx_dashboard:clear_i18n().

apps/emqx_dashboard/src/emqx_dashboard.erl

@@ -133,8 +133,8 @@ get_i18n() ->
     application:get_env(emqx_dashboard, i18n).
 
 init_i18n(File, Lang) when is_atom(Lang) ->
-    init_i18n(File, atom_to_list(Lang));
-init_i18n(File, Lang) when is_list(Lang) ->
+    init_i18n(File, atom_to_binary(Lang));
+init_i18n(File, Lang) when is_binary(Lang) ->
     Cache = hocon_schema:new_desc_cache(File),
     application:set_env(emqx_dashboard, i18n, #{lang => Lang, cache => Cache}).