Server Crash - runtime error: index out of range

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Background information

• Dendrite version or git SHA: 3d02c81
• SQLite3 or Postgres?: postgres (PostgreSQL) 15.4
• Running in Docker?: No
• go version: go version go1.21.1 linux/amd64

Description

• What is the problem: Server crashed with an index out of range error, dumping a fairly concise trace.
• Who is affected: Users of my instance, including myself
• How is this bug manifesting: dendrite_crash2.log
• When did this first appear: This is the first time I've seen this specific crash, the server was idle when it occurred.

Steps to reproduce

• Start a server with federation enabled
• Join a handful of populated rooms
• Leave it alone for a while (approx. 2 days)

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Potentially related third crash, happened 7 minutes after attempting a restart of the server:
dendrite_crash3.log
oh fun! This looks to be related to #3148. It was not.