diff --git a/bt/decorators/bt_always_fail.cpp b/bt/decorators/bt_always_fail.cpp
index 6dc112c..cfa42a4 100644
--- a/bt/decorators/bt_always_fail.cpp
+++ b/bt/decorators/bt_always_fail.cpp
@@ -3,7 +3,7 @@
 #include "bt_always_fail.h"
 
 int BTAlwaysFail::_tick(float p_delta) {
-	if (get_child(0)->execute(p_delta) == RUNNING) {
+	if (get_child_count() > 0 && get_child(0)->execute(p_delta) == RUNNING) {
 		return RUNNING;
 	}
 	return FAILURE;
diff --git a/bt/decorators/bt_always_succeed.cpp b/bt/decorators/bt_always_succeed.cpp
index a7beb03..a868a0b 100644
--- a/bt/decorators/bt_always_succeed.cpp
+++ b/bt/decorators/bt_always_succeed.cpp
@@ -3,7 +3,7 @@
 #include "bt_always_succeed.h"
 
 int BTAlwaysSucceed::_tick(float p_delta) {
-	if (get_child(0)->execute(p_delta) == RUNNING) {
+	if (get_child_count() > 0 && get_child(0)->execute(p_delta) == RUNNING) {
 		return RUNNING;
 	}
 	return SUCCESS;
diff --git a/bt/decorators/bt_delay.cpp b/bt/decorators/bt_delay.cpp
index 53153f1..4118a26 100644
--- a/bt/decorators/bt_delay.cpp
+++ b/bt/decorators/bt_delay.cpp
@@ -3,6 +3,7 @@
 #include "bt_delay.h"
 #include "core/array.h"
 #include "core/class_db.h"
+#include "core/error_macros.h"
 #include "core/object.h"
 #include "core/variant.h"
 
@@ -15,6 +16,7 @@ void BTDelay::_enter() {
 }
 
 int BTDelay::_tick(float p_delta) {
+	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator has no child.");
 	time_passed += p_delta;
 	if (time_passed <= seconds) {
 		return RUNNING;
diff --git a/bt/decorators/bt_invert.cpp b/bt/decorators/bt_invert.cpp
index 7bf90ef..a5fcd24 100644
--- a/bt/decorators/bt_invert.cpp
+++ b/bt/decorators/bt_invert.cpp
@@ -3,6 +3,7 @@
 #include "bt_invert.h"
 
 int BTInvert::_tick(float p_delta) {
+	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator has no child.");
 	int status = get_child(0)->execute(p_delta);
 	if (status == SUCCESS) {
 		status = FAILURE;
diff --git a/bt/decorators/bt_new_scope.cpp b/bt/decorators/bt_new_scope.cpp
index 70adf3c..423bde9 100644
--- a/bt/decorators/bt_new_scope.cpp
+++ b/bt/decorators/bt_new_scope.cpp
@@ -14,7 +14,7 @@ void BTNewScope::initialize(Object *p_agent, const Ref<Blackboard> &p_blackboard
 }
 
 int BTNewScope::_tick(float p_delta) {
-	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator doesn't have a child.");
+	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator has no child.");
 	return get_child(0)->execute(p_delta);
 }
 
diff --git a/bt/decorators/bt_probability.cpp b/bt/decorators/bt_probability.cpp
index e70c2fc..c656c17 100644
--- a/bt/decorators/bt_probability.cpp
+++ b/bt/decorators/bt_probability.cpp
@@ -8,6 +8,7 @@ String BTProbability::_generate_name() const {
 }
 
 int BTProbability::_tick(float p_delta) {
+	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator has no child.");
 	if (get_child(0)->get_status() == RUNNING or Math::randf() <= run_chance) {
 		return get_child(0)->execute(p_delta);
 	}
diff --git a/bt/decorators/bt_repeat.cpp b/bt/decorators/bt_repeat.cpp
index fb61449..607a4e1 100644
--- a/bt/decorators/bt_repeat.cpp
+++ b/bt/decorators/bt_repeat.cpp
@@ -13,6 +13,7 @@ void BTRepeat::_enter() {
 }
 
 int BTRepeat::_tick(float p_delta) {
+	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator has no child.");
 	int status = get_child(0)->execute(p_delta);
 	if (status == RUNNING) {
 		return RUNNING;
diff --git a/bt/decorators/bt_repeat_until_failure.cpp b/bt/decorators/bt_repeat_until_failure.cpp
index bd911f0..21e6b73 100644
--- a/bt/decorators/bt_repeat_until_failure.cpp
+++ b/bt/decorators/bt_repeat_until_failure.cpp
@@ -3,6 +3,7 @@
 #include "bt_repeat_until_failure.h"
 
 int BTRepeatUntilFailure::_tick(float p_delta) {
+	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator has no child.");
 	if (get_child(0)->execute(p_delta) == FAILURE) {
 		return SUCCESS;
 	}
diff --git a/bt/decorators/bt_repeat_until_success.cpp b/bt/decorators/bt_repeat_until_success.cpp
index aa2ad59..d9247d1 100644
--- a/bt/decorators/bt_repeat_until_success.cpp
+++ b/bt/decorators/bt_repeat_until_success.cpp
@@ -3,6 +3,7 @@
 #include "bt_repeat_until_success.h"
 
 int BTRepeatUntilSuccess::_tick(float p_delta) {
+	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator has no child.");
 	if (get_child(0)->execute(p_delta) == SUCCESS) {
 		return SUCCESS;
 	}
diff --git a/bt/decorators/bt_run_limit.cpp b/bt/decorators/bt_run_limit.cpp
index 4b616a9..643321c 100644
--- a/bt/decorators/bt_run_limit.cpp
+++ b/bt/decorators/bt_run_limit.cpp
@@ -7,6 +7,7 @@ String BTRunLimit::_generate_name() const {
 }
 
 int BTRunLimit::_tick(float p_delta) {
+	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator has no child.");
 	if (get_child(0)->get_status() != RUNNING) {
 		if (_num_runs >= run_limit) {
 			return FAILURE;
diff --git a/bt/decorators/bt_subtree.cpp b/bt/decorators/bt_subtree.cpp
index 50bd01e..e154fb1 100644
--- a/bt/decorators/bt_subtree.cpp
+++ b/bt/decorators/bt_subtree.cpp
@@ -29,6 +29,7 @@ Ref<BTTask> BTSubtree::clone() const {
 	if (!Engine::get_singleton()->is_editor_hint()) {
 		ERR_FAIL_COND_V_MSG(!subtree.is_valid(), copy, "Subtree is not assigned.");
 		ERR_FAIL_COND_V_MSG(!subtree->get_root_task().is_valid(), copy, "Subtree root task is not valid.");
+		ERR_FAIL_COND_V_MSG(get_child_count() != 0, copy, "Subtree prototype shouldn't have children.");
 
 		copy->add_child(subtree->get_root_task()->clone());
 	}
diff --git a/bt/decorators/bt_time_limit.cpp b/bt/decorators/bt_time_limit.cpp
index 68612cc..2ab6d2f 100644
--- a/bt/decorators/bt_time_limit.cpp
+++ b/bt/decorators/bt_time_limit.cpp
@@ -11,6 +11,7 @@ void BTTimeLimit::_enter() {
 }
 
 int BTTimeLimit::_tick(float p_delta) {
+	ERR_FAIL_COND_V_MSG(get_child_count() == 0, FAILURE, "BT decorator has no child.");
 	_time_passed += p_delta;
 	int status = get_child(0)->execute(p_delta);
 	if (status == RUNNING and _time_passed >= time_limit) {