Execute empty MULTI (#2423)

* Fix multi.exec with empty queue and previous watch

When calling exec on a multi instance which you did not use, no command is sent currently.

This is a problem for watched keys, because no EXEC means no unwatch, which might cause hard-to-debug problems.

Proposed Fix: Sending UNWATCH

* execute empty multi command (instead of skipping)

* Update index.ts

* Update index.ts

* Update multi-command.ts

* Update multi-command.ts

* Update multi-command.ts

* Update multi-command.ts

* short circuit empty pipelines

* Update index.ts

---------

Co-authored-by: Leibale <me@leibale.com>

packages/client/lib/cluster/multi-command.ts

@@ -120,11 +120,8 @@ export default class RedisClusterMultiCommand {
             return this.execAsPipeline();
         }
 
-        const commands = this.#multi.exec();
-        if (!commands) return [];
-
         return this.#multi.handleExecReplies(
-            await this.#executor(commands, this.#firstKey, RedisMultiCommand.generateChainId())
+            await this.#executor(this.#multi.queue, this.#firstKey, RedisMultiCommand.generateChainId())
         );
     }