refactor(core): use new backlink indexer (#7296)

packages/frontend/electron/src/helper/db/merge-update.ts

@@ -1,6 +1,12 @@
 import { applyUpdate, Doc as YDoc, encodeStateAsUpdate, transact } from 'yjs';
 
 export function mergeUpdate(updates: Uint8Array[]) {
+  if (updates.length === 0) {
+    return new Uint8Array();
+  }
+  if (updates.length === 1) {
+    return updates[0];
+  }
   const yDoc = new YDoc();
   transact(yDoc, () => {
     for (const update of updates) {