commit 81376ddba82a5f7c4adf221d65152bf71258f430
Author: Leszek Koltunski <leszek@distoretedandroid.org>
Date:   Tue Jun 28 12:13:16 2016 +0100

    Avoid a crash on exiting MessageSender

diff --git a/src/main/java/org/distorted/library/EffectMessageSender.java b/src/main/java/org/distorted/library/EffectMessageSender.java
index f67a02b..41ca82f 100644
--- a/src/main/java/org/distorted/library/EffectMessageSender.java
+++ b/src/main/java/org/distorted/library/EffectMessageSender.java
@@ -86,9 +86,12 @@ final class EffectMessageSender extends Thread
     {
     mRunning = false;
 
-    synchronized(mThis)
+    if( mThis!=null )
       {
-      mThis.notify();
+      synchronized(mThis)
+        {
+        mThis.notify();
+        }
       }
     }