For the curious: this wasn't completely for no reason, although it
appears that way from the outside. I deploy this code to AWS via the
CDK, and the Python Lambda function bundler in the CDK has two unwanted
properties:
1. The assets produced by the bundler are not reproducible, due to the
timestamps stored in the .pyc files. The bundler does nothing to
assist with this.
2. A bug (that was reported, and that the CDK maintainers converted from
an issue into discussion without any investigation) prevents the use
of arm64 runtimes with this bundler. This requires emulating x86_64
on my development machines, which are now only ARM.
... whereas the Rust function bundler I wrote does not have these
problems. So.
When authorized fetch mode is enabled on mastodon
https://docs.joinmastodon.org/admin/config/#authorized_fetch, mastodon
will signatures for endpoints which are used for
activitypub or an authenticated user for internal endpoints.
Since custom emojis is internal, it cannot be accessed without a
logged-in user.
This improves the error to make it more clear.
Andre_601