The error you're encountering is due to the fact that the JSON file exported from Spine 3.8.97 is not directly compatible with Spine 4.2.37. Spine JSON files are not backward compatible, meaning you cannot open a JSON file from an older version in a newer version without potential issues. To resolve this, you should open the JSON file in the same version of Spine that it was exported from (3.8.97), save it as a Spine project, and then open that project in the newer version of Spine. Alternatively, you can use the JsonRollback tool to convert the JSON to a format compatible with the newer version, but this is not always reliable for all features.
