spring-projectsGH-9694: Add null check when closing SocketChannel

Fixes: spring-projects#9694
Issue link: spring-projects#9694

- Add null check before closing socketChannel in catch block
- Prevents potential NullPointerException during error handling

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNioClientConnectionFactory.java

@@ -116,8 +116,11 @@ protected TcpConnectionSupport buildNewConnection() {
 		}
 		catch (IOException e) {
 			try {
-				socketChannel.close();
-			} catch (IOException e2) {
+				if (socketChannel != null) {
+					socketChannel.close();
+				}
+			}
+			catch (IOException e2) {
 				logger.error(e2, "Error closing socket channel");
 			}
 			throw new UncheckedIOException(e);