INT-4552: UDP: Catch and log async send exceptions

JIRA: https://jira.spring.io/browse/INT-4552

**Cherry-pick to 5.0.x**

(cherry picked from commit ce3ac36)

Author: garyrussell

spring-integration-ip/src/main/java/org/springframework/integration/ip/udp/UnicastReceivingChannelAdapter.java

@@ -139,7 +139,7 @@ public void run() {
 				throw new MessagingException("failed to receive DatagramPacket", e);
 			}
 		}
-		this.setListening(false);
+		setListening(false);
 	}
 
 	protected void sendAck(Message<byte[]> message) {
@@ -203,7 +203,12 @@ protected void doSend(final DatagramPacket packet) {
 			if (message.getHeaders().containsKey(IpHeaders.ACK_ADDRESS)) {
 				sendAck(message);
 			}
-			sendMessage(message);
+			try {
+				sendMessage(message);
+			}
+			catch (Exception e) {
+				this.logger.error("Failed to send message " + message, e);
+			}
 		}
 	}