[Discord bug] consistent 404 on a particular message

[blueridger]

We are getting a consistent 404 in our sourcecred/cred instance during the fetching of reactions on a discord props channel message. Note, this is not causing a failure (#3281), but might be messing with the props messages that get loaded, which could be very serious.

example run with error

discord message causing error: https://discord.com/channels/453243919774253079/679064720375808026/910623699311407124

Error: 404 Not Found on: https://discordapp.com/api/channels/679064720375808026/messages/910623699311407124/reactions/#%EF%B8%8F%E2%83%A3?after=0&limit=100; maybe bad serverUrl?
    at failIfMissing (webpack:///./src/plugins/discord/fetcher.js?:12:2677)
    at Fetcher._fetchJson (webpack:///./src/plugins/discord/fetcher.js?:12:143)
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async Fetcher.reactions (webpack:///./src/plugins/discord/fetcher.js?:12:2187)
    at async Mirror.addMessages (webpack:///./src/plugins/discord/mirror.js?:10:290)
    at async Mirror.update (webpack:///./src/plugins/discord/mirror.js?:8:511)
    at async DiscordPlugin.load (webpack:///./src/plugins/discord/plugin.js?:20:990)
    at async Promise.all (index 2)
    at async loadCommand (webpack:///./src/cli/load.js?:16:277)

I tried wiping the actions cache, which didn't fix it.