exception when android back button is pressed during scan
exception when android back button is pressed during scan

couldn't fix the actual crash so surrounded code in shutdowncamera with try/catch
benyao1201/Xamarin,sephirothwzc/ZXing.Net.Mobile,nied/ZXing.Net.Mobile,r2d2rigo/ZXing.Net.Mobile,Redth/ZXing.Net.Mobile,syphe/ZXing.Net.Mobile