Emoji substring search (#39353)

app/javascript/mastodon/actions/importer/emoji.ts

@@ -18,7 +18,7 @@ export async function importCustomEmoji(emojis: ApiCustomEmojiJSON[]) {
   );
 
   // If there's a mismatch, re-import all custom emojis.
-  if (existingEmojis.length < emojis.length) {
+  if (existingEmojis.length > 0 && existingEmojis.length < emojis.length) {
     await clearCache('custom');
     await loadCustomEmoji();