diff --git a/bt/behavior_tree.cpp b/bt/behavior_tree.cpp
index 5bd2a69..817b8a6 100644
--- a/bt/behavior_tree.cpp
+++ b/bt/behavior_tree.cpp
@@ -73,6 +73,8 @@ void BehaviorTree::copy_other(const Ref<BehaviorTree> &p_other) {
 
 Ref<BTTask> BehaviorTree::instantiate(Node *p_agent, const Ref<Blackboard> &p_blackboard, Node *p_scene_root) const {
 	ERR_FAIL_COND_V_MSG(root_task == nullptr, memnew(BTTask), "Trying to instance a behavior tree with no valid root task.");
+	ERR_FAIL_NULL_V_MSG(p_agent, memnew(BTTask), "Trying to instance a behavior tree with no valid agent.");
+	ERR_FAIL_NULL_V_MSG(p_scene_root, memnew(BTTask), "Trying to instance a behavior tree with no valid scene root.");
 	Ref<BTTask> inst = root_task->clone();
 	inst->initialize(p_agent, p_blackboard, p_scene_root);
 	return inst;
diff --git a/bt/bt_player.cpp b/bt/bt_player.cpp
index e491ec8..5a5ea0e 100644
--- a/bt/bt_player.cpp
+++ b/bt/bt_player.cpp
@@ -55,7 +55,7 @@ void BTPlayer::_load_tree() {
 	Node *agent = GET_NODE(this, agent_node);
 	ERR_FAIL_NULL_MSG(agent, vformat("BTPlayer: Initialization failed - can't get agent with path '%s'.", agent_node));
 	Node *scene_root = get_owner();
-	ERR_FAIL_NULL_MSG(scene_root, "BTPlayer: Initialization failed - can't get scene root (make sure the BTPlayer.owner is set).");
+	ERR_FAIL_NULL_MSG(scene_root, "BTPlayer: Initialization failed - can't get scene root (make sure the BTPlayer's owner property is set).");
 	tree_instance = behavior_tree->instantiate(agent, blackboard, scene_root);
 #ifdef DEBUG_ENABLED
 	if (IS_DEBUGGER_ACTIVE()) {
diff --git a/bt/bt_state.cpp b/bt/bt_state.cpp
index 08c40a6..1a29f03 100644
--- a/bt/bt_state.cpp
+++ b/bt/bt_state.cpp
@@ -52,7 +52,9 @@ void BTState::_update_blackboard_plan() {
 void BTState::_setup() {
 	LimboState::_setup();
 	ERR_FAIL_COND_MSG(behavior_tree.is_null(), "BTState: BehaviorTree is not assigned.");
-	tree_instance = behavior_tree->instantiate(get_agent(), get_blackboard(), get_owner());
+	Node *scene_root = get_owner();
+	ERR_FAIL_NULL_MSG(scene_root, "BTState: Initialization failed - can't get scene root (make sure the BTState's owner property is set).");
+	tree_instance = behavior_tree->instantiate(get_agent(), get_blackboard(), scene_root);
 
 #ifdef DEBUG_ENABLED
 	if (tree_instance.is_valid() && IS_DEBUGGER_ACTIVE()) {