Fix build errors

frontend/src/components/DirViewer/PreviewImage.vue

@@ -1,9 +1,9 @@
 <script setup async lang="ts">
-import type { TokenInjectType } from '@/api';
+import type { TokenInjectType, Responses } from '@/api';
 import { inject, ref } from 'vue';
 import { NImage, NIcon } from 'naive-ui';
 import { Image, Music, Video, Document } from '@vicons/carbon';
-import { check_token, FS, isErrorResponse, Responses } from '@/api';
+import { check_token, FS, isErrorResponse } from '@/api';
 
 const props = defineProps<{
 	node: Responses.GetNodeEntry;
@@ -75,7 +75,7 @@ if (token) {
 			fill="currentColor"
 		>
 			<tspan x="0.4" y="7.5">
-				{{ node.name.split('.').pop().toUpperCase() }}
+				{{ (node.name.split('.').pop() ?? '').toUpperCase() }}
 			</tspan>
 		</text>
 	</svg>