Fix unhandled PROPERTY_HINT_NO_NODEPATH warning

Due to upstream change:

	6f7525c396

doc/source/behavior-trees/using-blackboard.rst

@@ -34,6 +34,21 @@ Here's an example of how you can interact with the :ref:`Blackboard<class_Blackb
         if blackboard.has_var(speed_var):
             # ...
 
+If you are accessing a variable that holds an object instance, and it is
+expected that the instance may be null or freed, you can do it like this:
+
+.. code:: gdscript
+
+    @export var object_var: StringName = &"object"
+
+    func _tick(delta: float) -> Status:
+        # Get object instance stored in the "object" variable.
+        # - Important: Avoid specifying a type for "obj" in GDScript
+        #   to prevent errors when the instance is freed.
+        var obj = blackboard.get_var(object_var)
+        if is_instance_valid(obj):
+            # ...
+
 It is recommended to suffix variable name properties with ``_var``, like in the example above, which enables the
 inspector to provide a more convenient property editor for the variable. This editor
 allows you to select or add the variable to the blackboard plan, and provides a
@@ -107,10 +122,13 @@ This creates a "blackboard scope chain," where each :ref:`Blackboard<class_Black
 and there is no limit to how many blackboards can be in this chain.
 It's important to note that the :ref:`Blackboard<class_Blackboard>` doesn't modify values in the parent scopes.
 
-Some scopes are created automatically. For instance, when using the :ref:`BTNewScope<class_BTNewScope>`
-and :ref:`BTSubtree<class_BTSubtree>` decorators, or when a :ref:`LimboState<class_LimboState>`
-has non-empty blackboard plan defined, or when a root-level :ref:`LimboHSM<class_LimboHSM>`
-node is used. Such scopes prevent naming collisions between contextually separate environments.
+Scopes are created automatically to prevent naming collisions between contextually separate environments:
+
+- Within :ref:`BTNewScope<class_BTNewScope>`.
+- Under :ref:`BTSubtree<class_BTSubtree>` decorators.
+- With :ref:`LimboState<class_LimboState>` that have a non-empty blackboard plan defined.
+- Under :ref:`LimboHSM<class_LimboHSM>` nodes: A new scope is created at the root level,
+  and each :ref:`BTState<class_BTState>` child also receives its own separate scope.
 
 Sharing data between several agents
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~