Fix warnings

lua/piemenu/core/menu.lua

@@ -60,8 +60,9 @@ function Menus.parse(name, raw_setting)
     end
   end
 
-  local setting, err = Setting.new(raw_setting)
-  if err then
+  local setting = Setting.new(raw_setting)
+  if type(setting) == "string" then
+    local err = setting
     return err
   end
 

lua/piemenu/core/setting.lua

@@ -34,18 +34,18 @@ function Setting.new(raw_setting)
     animation = { data.animation, "table" },
   })
   if base_err then
-    return nil, base_err
+    return base_err
   end
 
   local anim_err = validatelib.validate({
     ["animation.duration"] = validatelib.not_negative(data.animation.duration),
   })
   if anim_err then
-    return nil, anim_err
+    return anim_err
   end
 
   local tbl = { _data = data }
-  return setmetatable(tbl, Setting), nil
+  return setmetatable(tbl, Setting)
 end
 
 function Setting.default_values()

lua/piemenu/view/init.lua

@@ -21,9 +21,10 @@ function View.open(name, raw_setting)
     return err
   end
 
-  local setting, merge_err = menus.setting:merge(raw_setting)
-  if merge_err then
-    return merge_err
+  local setting = menus.setting:merge(raw_setting)
+  if type(setting) == "string" then
+    local err = setting
+    return err
   end
 
   local view_setting = setting:for_view()