### 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)

List<BlendKey> to_erase;
	HashMap<BlendKey, double, BlendKey> to_insert;
	for (const KeyValue<BlendKey, double> &E : blend_times) {
		BlendKey bk = E.key;
		BlendKey new_bk = bk;
		bool erase = false;
		if (bk.from == p_from_name) {
			new_bk.from = p_to_name;
			erase = true;
		}
		if (bk.to == p_from_name) {