Handle backup site name error

dashboard/src/components/BackupSiteConfigDialog.vue

@@ -47,7 +47,9 @@ async function onSubmit() {
 
   let [error] = await backupSitesModel.setName(site.value.id, name.value);
   if (error) {
-    formError.value.generic = error.body ? error.body.message : 'Internal error';
+    if (error.status === 400) formError.value.name = error.body.message;
+    else formError.value.generic = error.body ? error.body.message : 'Internal error';
+
     busy.value = false;
     return console.error(error);
   }
@@ -188,13 +190,14 @@ defineExpose({
           <fieldset :disabled="busy">
             <input style="display: none;" type="submit"/>
 
-            <div class="error-label" v-if="formError.generic">{{ formError.generic }}</div>
-
             <FormGroup>
               <label for="backupSiteNameInput">{{ $t('backups.configureBackupStorage.name') }}</label>
               <TextInput id="backupSiteNameInput" v-model="name" required/>
+              <div class="error-label" v-if="formError.name">{{ formError.name }}</div>
             </FormGroup>
 
+            <div class="error-label" v-if="formError.generic">{{ formError.generic }}</div>
+
             <FormGroup v-if="site.provider && site.config">
               <label><i v-if="site.encrypted" class="fa-solid fa-lock"></i> Storage: <b>{{ site.provider }} ({{ site.format }}) </b></label>
               <div>