[core] WEBJS - fix error for message.ack

TypeError: You provided 'null' where a stream was expected.

src/core/engines/webjs/session.webjs.core.ts

@@ -1509,6 +1509,7 @@ export class WhatsappSessionWebJSCore extends WhatsappSession {
       mergeMap((node) =>
         TagReceiptNodeToReceiptEvent(node as any, this.getSessionMeInfo()),
       ),
+      filter(Boolean),
       mergeMap(this.TagReceiptToMessageAck.bind(this)),
       filter((ack) => isJidGroup(ack.to) || isJidStatusBroadcast(ack.to)),
     );