Fix crash on calling play() in a uninitialized AnimatedSprite2D

When AnimatedSprite2D::play() was called before SpriteFrames has been initialized, a crach occurred (issue #46013).

Modification : An error message on null check test has been added to prevent crash.

Fix #46013.

scene/2d/animated_sprite_2d.cpp

@@ -382,6 +382,7 @@ bool AnimatedSprite2D::_is_playing() const {
 }
 
 void AnimatedSprite2D::play(const StringName &p_animation, const bool p_backwards) {
+	ERR_FAIL_NULL_MSG(frames, "Can't play AnimatedSprite2D without a valid SpriteFrames resource.");
 	backwards = p_backwards;
 
 	if (p_animation) {