- return null if no packet received

git-svn-id: https://svn.code.sf.net/p/libusbjava/code/trunk@93 94ad28fe-ef68-46b1-9651-e7ae4fcf1c4c

mcdp/src/ch/ntb/mcdp/uart/blackbox/Uart0.java

@@ -61,6 +61,9 @@ public class Uart0 {
 		DataPacket packet;
 		try {
 			packet = Dispatch.readUART();
+			if (packet == null) {
+				return null;
+			}
 			return packet.data;
 		} catch (Exception e) {
 			return null;