bug fix for #1071 When --display_data=true, Failed running control_robot. (#1073)

Author: masato-ka

lerobot/common/robot_devices/control_utils.py

@@ -250,6 +250,7 @@ def control_loop(
             observation, action = robot.teleop_step(record_data=True)
         else:
             observation = robot.capture_observation()
+            action = None
 
             if policy is not None:
                 pred_action = predict_action(
@@ -266,9 +267,10 @@ def control_loop(
 
         # TODO(Steven): This should be more general (for RemoteRobot instead of checking the name, but anyways it will change soon)
         if (display_data and not is_headless()) or (display_data and robot.robot_type.startswith("lekiwi")):
-            for k, v in action.items():
-                for i, vv in enumerate(v):
-                    rr.log(f"sent_{k}_{i}", rr.Scalar(vv.numpy()))
+            if action is not None:
+                for k, v in action.items():
+                    for i, vv in enumerate(v):
+                        rr.log(f"sent_{k}_{i}", rr.Scalar(vv.numpy()))
 
             image_keys = [key for key in observation if "image" in key]
             for key in image_keys: