fix: avoid break when drop wal table failed (#806)

* avoid break when drop wal failed

* polish

* fmt

Author: MichaelLeeHZ

wal/src/table_kv_impl/namespace.rs

@@ -1441,7 +1441,9 @@ fn purge_buckets<T: TableKv>(
     for bucket in &buckets {
         // Delete all tables of this bucket.
         for table_name in &bucket.wal_shard_names {
-            table_kv.drop_table(table_name).map_err(Box::new)?;
+            let _ = table_kv.drop_table(table_name).map_err(|e| {
+                error!("Purge buckets drop table failed, table:{table_name}, err:{e}");
+            });
         }
 
         // All tables of this bucket have been dropped, we can remove the bucket record