🐛 add null check for csrf element content

[parrotmac]

Issue

On a fresh clone of the lustre repo, when running e.g. examples/06-server-components/05-publish-subscribe (also happening on at least 06-/{04-,06-}) the following is thrown in the browser console:

Uncaught TypeError: Cannot read properties of null (reading 'getAttribute')
    at #m (runtime.mjs:2:10316)
    at de.attributeChangedCallback (runtime.mjs:2:7806)
    at runtime.mjs:2:13482

This appears to happen if the csrf meta element isn't found, so meta is null here.

Fix

Added ONLY optional chaining to src/lustre/runtime/client/server_component.ffi.mjs, then ran gleam run -m build, resulting in all other changes present.

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Validating this fix also required updating mist to >= v6.0.0, though that appears to be a separate issue.

[parrotmac]

Should the build process have removed these lines? Or did I mess something up?

[hayleigh-dot-dev]

Ah yeah that's fine. The server component runtime is built fresh on every release so the releases are never out of sync but between releases sometimes we forget to run the build and commit the artefact. It's kinda an awkward dance at the moment, but yeah this change is expected don't worry!

[hayleigh-dot-dev]

Oh thank you, that was a silly mistake. Good catch! 💕