How to ensure the robot's horizon is in a valid range?

Hi guys, I was playing robothor ObjNav tasks recently and it was really interesting! Thanks for your great work!

I have a few questions about the actions of the robot:

1. I checked out the example_submission file and found that the "success" of an "Stop" action can be either be true of false. Why the simple "Stop" action can produce both true or false outcomes? Does the success of the "Stop" action indicate the final success of the entire trajectory? I don't really think so because I also noticed that when "Stop"'s "success" is false, the final result is guaranteed to be false. However, when "Stop"'s "success" is true, still the final results can be false.

2. How to guarantee the horizons of the robot are in the valid range? I am aware that the expected horizon for locobot is {-30, 0, +30}, as stated in the documentation. But, how to ensure when the horizon is 30, another "LookDown" will not performed? Or those actions are deemed invalid and will not be executed? I mean, I realized that the horizon of 60, or -60 are possible, I just want to know how to ensure they are not exist in the submissions, thanks in advance!