error handling for deserialize

WatcherAgent/src/config.rs

@@ -36,6 +36,13 @@ impl Settings {
                     .prefix_separator("_"),
             );
 
-        builder.build()?.try_deserialize()
+        let config = builder.build()?;
+
+        // Try to deserialize and provide error message
+        config.try_deserialize().map_err(|e| {
+            eprintln!("Configuration error: {}", e);
+            eprintln!("Required fields: server.url, app.heartbeat_interval_secs, app.metrics_interval_secs, app.port");
+            e
+        })
     }
 }