Fixed a crash in BarcodeScannerView

Author: ajungg

ui/src/main/java/io/snabble/sdk/ui/scanner/BarcodeScannerView.java

@@ -580,6 +580,7 @@ public void run() {
                     camera.release();
                     camera = null;
                     running = false;
+                    decodeEnabled = false;
                 }
 
                 startRequested = false;