Prevent crash when returning empty (like a cancelled scan) from the barcode scanner. Fixes #209.

app/src/main/java/org/transdroid/core/gui/TorrentsActivity.java

@@ -774,10 +774,12 @@ public class TorrentsActivity extends ActionBarActivity implements TorrentTasksE
 	@Background
 	@OnActivityResult(BarcodeHelper.ACTIVITY_BARCODE_ADDTORRENT)
 	public void onBarcodeScanned(int resultCode, Intent data) {
+		if (data != null) {
 			// We receive from the helper either a URL (as string) or a query we can start a search for
 			String query = BarcodeHelper.handleScanResult(resultCode, data, navigationHelper.enableSearchUi());
 			onBarcodeScanHandled(data.getStringExtra("SCAN_RESULT"), query);
 		}
+	}
 
 	@UiThread
 	protected void onBarcodeScanHandled(String barcode, String result) {