Return a value from xoptional_assembly_storage::data() - #2955

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Failed to save: Unable to reserve cache with key micromamba-downloads--osx-arm64, another job may be creating this cache.