display message on GDT transaction list when GDT server is not reachable

frontend/src/locales/de.json

@@ -109,6 +109,7 @@
     "funding": "Zu den Förderbeiträgen",
     "gdt-received": "GradidoTransform (GDT) erhalten",
     "no-transactions": "Du hast noch keine GradidoTransform (GDT).",
+    "not-reachable": "Der GDT Server ist nicht erreichbar.",
     "publisher": "Dein geworbenes Mitglied hat einen Beitrag bezahlt",
     "raise": "Erhöhung",
     "recruited-member": "Eingeladenes Mitglied"

frontend/src/locales/en.json

@@ -109,6 +109,7 @@
     "funding": "To the funding contributions",
     "gdt-received": "GradidoTransform (GDT) received",
     "no-transactions": "You do not have GradidoTransform (GDT) yet.",
+    "not-reachable": "The GDT Server is not reachable.",
     "publisher": "A member you referred has paid a contribution",
     "raise": "Increase",
     "recruited-member": "Invited member"

frontend/src/views/Pages/AccountOverview/GdtTransactionList.vue

@@ -8,6 +8,9 @@
           {{ $t('gdt.funding') }}
         </b-button>
       </div>
+      <div v-else-if="typeof transactionGdtCount === 'object'" class="text-center">
+        {{ $t('gdt.not-reachable') }}
+      </div>
       <div
         v-else
         v-for="{ id, amount, date, comment, gdtEntryType, factor, gdt } in transactionsGdt"