Problem with Exercise 9.13 : cannot land a drone and result of the action doesn't appear

The challenge here is that you need to understand any code you copy because it may not work out of the box for you and because you may not copy it right.

We don’t encourage students just copying the solutions - the intention is not to give you something that works perfectly, but to guide you in fixing your own code. Please develop your own logic for the exercise.

The key to the problem is in the error

result.result must be an integer...

and this error is happening when the action is about to return a result.

As for the drone not landing, you can check the following: