Fix crash at startup

app/src/main/AndroidManifest.xml

@@ -8,6 +8,7 @@
     <uses-permission android:name="android.permission.RECEIVE_SMS" />
     <uses-permission android:name="android.permission.READ_PHONE_STATE" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
 
     <application
         tools:replace="allowBackup,label"

app/src/main/java/eu/droogers/smsmatrix/MatrixService.java

@@ -113,7 +113,9 @@ public class MatrixService extends Service {
 
     @Override
     public void onDestroy() {
-        mx.destroy();
+        if (mx != null) {
+            mx.destroy();
+        }
         this.mms.stopMMSMonitoring();
         this.mms = null;
         super.onDestroy();