To resolve the error you're encountering in Unity, you need to ensure that the object you're working with has a reference to a SkeletonDataAsset. The error message indicates that the object requires this reference to function correctly. When you add a SkeletonAnimation script, it automatically handles this requirement by linking to the necessary SkeletonDataAsset. If you want to expose a reference to an animation without attaching a SkeletonAnimation script, you must manually ensure that the SkeletonDataAsset is correctly referenced in your script or setup.
One workaround is to create a separate script that manages the SkeletonDataAsset reference and links it to the animation you want to expose. This script can be attached to the same GameObject or another relevant object in your scene. Ensure that the SkeletonDataAsset is correctly assigned in the Inspector to avoid runtime errors.