It looks like you're encountering the same error across different scenarios involving the state cookie in Spotify Auth. I already provided a comprehensive set of troubleshooting steps in a previous answer. If you've gone through them and the issue persists, consider these additional options:

More Debugging Steps:

1. Double-Check Config: Ensure your Spotify Developer Dashboard settings match your application, especially redirect URIs.

2. Stack Trace: Check the complete error stack trace for more context on where the error is being thrown.

3. Code Examination: Sometimes errors are thrown in bundled/minified code, making it hard to debug. Use source maps or similar tools to find the original code location of the error.

4. Local Vs Production: If you are experiencing this issue in a production environment, try to replicate it in a local/dev environment where you have more control.

5. Issues or Pull Requests: Check if there are any issues or pull requests related to this problem in the repository where you found the spotify-auth code.

6. Community Support: Sometimes issues like this are better discussed in a community forum where other developers who've faced similar issues can help you out.

Feel free to provide more specific information about your setup if the issue persists.