Before jumping into the rest of the chapter, we should learn how to debug behavior trees. Actually, there are many methods, and some we will explore later in this chapter (with stats) and in the next one (such as the gameplay debugger).
However, I wanted to point out that it is possible to see the execution of a behavior tree. If you leave the behavior tree editor open while you play the game, you will see highlighted the current branch being executed on the behavior tree, and which decorators are blocked. Also, in the blackboard panel, it is possible to check the current values for each of the blackboard values. Here is an example from the designing behavior trees project:
Also, if you have more than one enemy running a behavior tree, you can change which one to view from the top menu, as shown: