From 8b79d35a70cceb545fde5dd9e01357edbd0a8956 Mon Sep 17 00:00:00 2001
From: BishyanKar <bishyankar99@gmail.com>
Date: Thu, 28 Oct 2021 16:06:04 +0530
Subject: [PATCH] Fixes #2271 crash on closing WaveGenerator Screen

---
 app/src/main/java/io/pslab/activity/WaveGeneratorActivity.java | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/app/src/main/java/io/pslab/activity/WaveGeneratorActivity.java b/app/src/main/java/io/pslab/activity/WaveGeneratorActivity.java
index c3347df3b..3f492a731 100644
--- a/app/src/main/java/io/pslab/activity/WaveGeneratorActivity.java
+++ b/app/src/main/java/io/pslab/activity/WaveGeneratorActivity.java
@@ -1370,7 +1370,8 @@ protected void onCancelled() {
     @Override
     public void onBackPressed() {
         super.onBackPressed();
-        produceSoundTask.cancel(true);
+        if(produceSoundTask != null)
+            produceSoundTask.cancel(true);
         produceSoundTask = null;
         isPlayingSound = false;
     }