fix: server correctly handles non-JSON payloads

This commit addresses the server not handling non-JSON payloads correctly.
Fixes #2

server/src/main.py

@@ -83,6 +83,8 @@ class Server:
                 else:
                     command = "nop"
             conn.send(json.dumps({"command": command}).encode())
+        except json.decoder.JSONDecodeError:
+            logger.error(f"Invalid JSON received from {addr}")
         except Exception as e:
             logger.error(f"Error handling agent {agent_id}: {e}")
         finally: