### Godot version

4.0.beta13

### System information

Windows 10

### Issue description

When you call the `seek()` function without a current animation it outputs `Condition "!playback.current.from" is true.` to the debugger.

I was getting the error above whenever I would call `stop()` on an AnimationPlayer when it didn't have a playing animation. I realized that `stop()` also calls the `seek()` function.

I would expect the `seek()` and `stop()` functions to just do nothing, instead of throwing errors, if there isn't a current animation, or at least show an error that says that there is no animation to seek/stop.

This is the same issue that was described here: [#6122](https://github.com/godotengine/godot/issues/6122)

### Steps to reproduce

- Create an AnimationPlayer node.
- Don't have it play any animations.
- Call the `seek()` function.

### Minimal reproduction project

[seek_issue.zip](https://github.com/godotengine/godot/files/10442071/seek_issue.zip)

ERR_FAIL_COND_V_MSG(!animation_set.has(p_name), Ref<Animation>(), vformat("Animation not found: \"%s\".", p_name));
	const AnimationData &anim_data = animation_set[p_name];
	return anim_data.animation;
}
void AnimationPlayer::get_animation_list(List<StringName> *p_animations) const {
	List<String> anims;
	for (const KeyValue<StringName, AnimationData> &E : animation_set) {
		anims.push_back(E.key);
	}
	anims.sort();
	for (const String &E : anims) {
		p_animations->push_back(E);
	}
}
void AnimationPlayer::set_blend_time(const StringName &p_animation1, const StringName &p_animation2, double p_time) {
	ERR_FAIL_COND_MSG(!animation_set.has(p_animation1), vformat("Animation not found: %s.", p_animation1));
	ERR_FAIL_COND_MSG(!animation_set.has(p_animation2), vformat("Animation not found: %s.", p_animation2));
	ERR_FAIL_COND_MSG(p_time < 0, "Blend time cannot be smaller than 0.");
	BlendKey bk;
	bk.from = p_animation1;
	bk.to = p_animation2;
	if (p_time == 0) {
		blend_times.erase(bk);
	} else {
		blend_times[bk] = p_time;
	}
}
double AnimationPlayer::get_blend_time(const StringName &p_animation1, const StringName &p_animation2) const {