From ee9fba07ac9e51006c70548bdec40575a895830a Mon Sep 17 00:00:00 2001
From: Vomatec Innovations <31130956+vomatec@users.noreply.github.com>
Date: Tue, 5 Sep 2017 20:18:21 +0200
Subject: [PATCH] I fixed the app crashing exception for Android after pressing
 'back' key multiple times after opening the print window. (#149)

---
 src/android/Printer.java | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/android/Printer.java b/src/android/Printer.java
index eb6b6dc..0f5f467 100644
--- a/src/android/Printer.java
+++ b/src/android/Printer.java
@@ -347,14 +347,16 @@ public class Printer extends CordovaPlugin {
      */
     @Override
     public void onDestroy() {
-        pm.unsetOnPrintJobStateChangeListener();
+ 	if(pm != null && listener != null && command != null && view != null) {
+       	   pm.unsetOnPrintJobStateChangeListener();
 
-        pm       = null;
-        listener = null;
-        command  = null;
-        view     = null;
+       	   pm       = null;
+           listener = null;
+           command  = null;
+           view     = null;
 
-        super.onDestroy();
+           super.onDestroy();
+	}
     }
 
     /**