[Standalone] Print log when configuration is failed to load
### Motivation
Print log when configuration is failed to load.
### Modifications
Print log when config is null.
@@ -250,6 +250,7 @@ public class PulsarStandalone implements AutoCloseable {
public void start() throws Exception {
if (config == null) {
+ log.error("Failed to load configuration");
System.exit(1);
}
