Removing Action Space comparison with CTRL for MuJoco Envs (#604)

Co-authored-by: Mark Towers <[email protected]>

Author: reginald-mclean

Diff for: gymnasium/envs/mujoco/mujoco_env.py

@@ -170,9 +170,9 @@ def do_simulation(self, ctrl, n_frames) -> None:
         Step the simulation n number of frames and applying a control action.
         """
         # Check control input is contained in the action space
-        if np.array(ctrl).shape != self.action_space.shape:
+        if np.array(ctrl).shape != (self.model.nu,):
             raise ValueError(
-                f"Action dimension mismatch. Expected {self.action_space.shape}, found {np.array(ctrl).shape}"
+                f"Action dimension mismatch. Expected {(self.model.nu,)}, found {np.array(ctrl).shape}"
             )
         self._step_mujoco_simulation(ctrl, n_frames)