safe_velocity isn't declared in this script. Changing it to new_velocity makes it funciton correctly.
@@ -157,7 +157,7 @@ a NavigationAgent3D for path movement.
new_velocity = new_velocity.normalized()
new_velocity = new_velocity * movement_speed
- velocity = safe_velocity
+ velocity = new_velocity
move_and_slide()
.. code-tab:: csharp C#