✨(react) fix translations and add missing translations

This commit improves the translations method to handle undefined values
gracefully and adds several missing translations for modals in the
French locale.

.changeset/warm-trees-act.md

@@ -0,0 +1,5 @@
+---
+"@openfun/cunningham-react": patch
+---
+
+Fix translations method and added missing translations

packages/react/src/components/Provider/index.tsx

@@ -47,7 +47,10 @@ const findTranslation = (
   locale: TranslationSet,
 ): string | undefined => {
   const [namespace, ...keys] = key.split(".");
-  return keys.reduce((acc, subKey) => acc[subKey], (locale as any)[namespace]);
+  return keys.reduce(
+    (acc, subKey) => acc?.[subKey],
+    (locale as any)[namespace],
+  );
 };
 
 export const CunninghamProvider = ({

packages/react/src/locales/fr-FR.json

@@ -46,6 +46,27 @@
         "year_select_button_aria_label": "Sélectionner une année",
         "month_select_button_aria_label": "Sélectionner un mois"
       }
+    },
+    "modals": {
+      "helpers": {
+        "delete_confirmation": {
+          "title": "Êtes-vous sûr ?",
+          "children": "Êtes-vous sûr de vouloir supprimer cet élément ?",
+          "cancel": "Annuler",
+          "delete": "Supprimer"
+        },
+        "confirmation": {
+          "title": "Êtes-vous sûr ?",
+          "children": "Êtes-vous sûr de vouloir faire cela ?",
+          "cancel": "Annuler",
+          "yes": "Oui"
+        },
+        "disclaimer": {
+          "title": "Avertissement",
+          "children": "Ceci est un avertissement",
+          "ok": "Ok"
+        }
+      }
     }
   }
 }