is it ok with the output that i get? it does nothing but .... sometimes it is there, sometimes it disappear
In short, yes these errors are fine.
The output you are seeing is due to the use of the tool keyword at the top of the script.
This keyword makes the code run in the editor, and the errors you are getting are specific to when the code is running in the editor. It will not affect the game.
The error most likely happens when creating a pressure plate, before you add a door as a child of it. This is because the code tries to get and operate on a child node named Door.
Adding the missing door and reloading the scene should get rid of the errors.