Mastodon Docker Error Fix

I am currently facing an issue with my Mastodon Docker instance. Whenever I try to access the platform, I am met with an error message that reads We're sorry, but something went wrong on our end..

The log shows
"ActionView::Template::Error (undefined method `[]' for nil:NilClass)". This problem occurs on all pages, rendering the instance inaccessible.

The ideal freelancer for this project should have a strong background in system administration and experience with Docker and Ruby on Rails. The successful candidate should be familiar with troubleshooting and resolving errors in Mastodon instances, particularly those running in docker.

Specific requirements for this project include:
- Identifying the root cause of the issue
- Implementing the necessary fixes to ensure the platform is accessible on all pages
- Providing recommendations on how to prevent similar issues in the future
- Ensuring the overall performance of the Mastodon instance is not compromised in the process
- document on how to properly update mastodon instances

Please provide an overview of how you plan to address this issue, as well as your relevant experience with similar projects.