improve error message

apps/app/public/static/locales/en_US/translation.json

@@ -743,7 +743,8 @@
   "pagetree": {
     "cannot_rename_a_title_that_contains_slash": "Cannot rename a title that contains '/'",
     "you_cannot_move_this_page_now": "You cannot move this page now",
-    "something_went_wrong_with_moving_page": "Something went wrong with moving page"
+    "something_went_wrong_with_moving_page": "Something went wrong with moving page",
+    "error_retrieving_the_pagetree": "Error occurred while retrieving the PageTree"
   },
   "duplicated_page_alert": {
     "same_page_name_exists": "Same page name exits as「{{pageName}}」",

apps/app/public/static/locales/fr_FR/translation.json

@@ -736,7 +736,8 @@
   "pagetree": {
     "cannot_rename_a_title_that_contains_slash": "Renommage impossible lorsque le titre contient '/'",
     "you_cannot_move_this_page_now": "Déplacement de la page impossible",
-    "something_went_wrong_with_moving_page": "Échec de déplacement de la page"
+    "something_went_wrong_with_moving_page": "Échec de déplacement de la page",
+    "error_retrieving_the_pagetree": "Une erreur s'est produite lors de la récupération de l'arbre des pages"
   },
   "duplicated_page_alert": {
     "same_page_name_exists": "Une page avec ce nom 「{{pageName}}」 existe déjà",

apps/app/public/static/locales/ja_JP/translation.json

@@ -775,7 +775,8 @@
   "pagetree": {
     "cannot_rename_a_title_that_contains_slash": "`/` が含まれているタイトルにリネームできません",
     "you_cannot_move_this_page_now": "現在、このページを移動することはできません",
-    "something_went_wrong_with_moving_page": "ページの移動に問題が発生しました"
+    "something_went_wrong_with_moving_page": "ページの移動に問題が発生しました",
+    "error_retrieving_the_pagetree": "ページツリーの取得中にエラーが発生しました"
   },
   "duplicated_page_alert": {
     "same_page_name_exists": "ページ名 「{{pageName}}」が重複しています",

apps/app/public/static/locales/zh_CN/translation.json

@@ -745,7 +745,8 @@
   "pagetree": {
     "cannot_rename_a_title_that_contains_slash": "不能重命名包含 ’/' 的标题",
     "you_cannot_move_this_page_now": "你现在不能移动这个页面",
-    "something_went_wrong_with_moving_page": "移动页面时出了问题"
+    "something_went_wrong_with_moving_page": "移动页面时出了问题",
+    "error_retrieving_the_pagetree": "检索页面树时发生错误"
   },
   "duplicated_page_alert": {
     "same_page_name_exists": "页面名称「{{pageName}}」是重复的",

apps/app/src/client/components/ItemsTree/ItemsTree.tsx

@@ -134,8 +134,7 @@ export const ItemsTree = (props: ItemsTreeProps): JSX.Element => {
 
 
   if (error != null) {
-    // TODO: improve message
-    toastError('Error occurred while fetching pages to render PageTree');
+    toastError(t('pagetree.error_retrieving_the_pagetree'));
     return <></>;
   }