From 6dd53fff4851f8f59222f01495f7a61385612e30 Mon Sep 17 00:00:00 2001
From: Steve Gill <stevengill@slack-corp.com>
Date: Fri, 10 Jan 2020 16:57:29 -0800
Subject: [PATCH] fixed ack in expressreceiver firing twice. Issue #327

---
 src/ExpressReceiver.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/ExpressReceiver.ts b/src/ExpressReceiver.ts
index 7a810ef3c..ca2f094ca 100644
--- a/src/ExpressReceiver.ts
+++ b/src/ExpressReceiver.ts
@@ -88,8 +88,9 @@ export default class ExpressReceiver extends EventEmitter implements Receiver {
           clearTimeout(timer);
           timer = undefined;
 
-          if (!response) res.send('');
-          if (typeof response === 'string') {
+          if (!response) {
+            res.send('');
+          } else if (typeof response === 'string') {
             res.send(response);
           } else {
             res.json(response);