fix(ckb-indexer)!: wait for the next n blocks

.changeset/eight-pots-invent.md

@@ -2,4 +2,4 @@
 "@ckb-lumos/lumos": minor
 ---
 
-BREAKING CHANGE: refine the export structure
+**BREAKING CHANGE**: refine the export structure

.changeset/purple-countries-fetch.md

@@ -0,0 +1,5 @@
+---
+"@ckb-lumos/ckb-indexer": minor
+---
+
+**BREAKING CHANGE**: correct the semantic of the `waitForSync`

packages/ckb-indexer/src/indexer.ts

@@ -84,14 +84,14 @@
     return new Promise((resolve) => setTimeout(resolve, timeout));
   }
 
-  async waitForSync(blockDifference = 0): Promise<void> {
+  async waitForSync(nextNBlocks = 0): Promise<void> {
     const rpcTipNumber = parseInt(
       (await this.getCkbRpc().getTipHeader()).number,
       16
     );
     while (true) {
       const indexerTipNumber = parseInt((await this.tip()).blockNumber, 16);
-      if (indexerTipNumber + blockDifference >= rpcTipNumber) {
+      if (indexerTipNumber - nextNBlocks >= rpcTipNumber) {
         return;
       }
       await this.asyncSleep(1000);