Reject multi.exec() promise with ClientClosedError after client disconnect (redis#2293)

* Add reject multi chain on client disconnect assertion to client test suite

* Reject multi chain exec with client closed error after client disconnect

Author: dabroek

packages/client/lib/client/index.spec.ts

@@ -425,6 +425,19 @@ describe('Client', () => {
             );
         }, GLOBAL.SERVERS.OPEN);
 
+        testUtils.testWithClient('should reject the whole chain upon client disconnect', async client => {
+            await client.disconnect();
+
+            return assert.rejects(
+                client.multi()
+                    .ping()
+                    .set('key', 'value')
+                    .get('key')
+                    .exec(),
+                ClientClosedError
+            );
+        }, GLOBAL.SERVERS.OPEN);
+
         testUtils.testWithClient('with script', async client => {
             assert.deepEqual(
                 await client.multi()

packages/client/lib/client/index.ts

@@ -611,6 +611,10 @@ export default class RedisClient<
         selectedDB?: number,
         chainId?: symbol
     ): Promise<Array<RedisCommandRawReply>> {
+        if (!this.#socket.isOpen) {
+            return Promise.reject(new ClientClosedError());
+        }
+
         const promise = Promise.all(
             commands.map(({ args }) => {
                 return this.#queue.addCommand(args, { chainId });