Panic when `sync_with_custom_puppets` is enabled

I noticed my other mautrix bridges have sync_with_custom_puppets, so I figured I'd try enabling it (I don't know what it does, but sure!). I saw that ephemeral_events should be disabled, so I disabled that too. I then launch mautrix-imessage and get a panic pretty quickly:

2024-03-05T21:20:16-08:00 INF Successfully automatically enabled custom puppet module=User/@jacob:mydomain.com
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x20 pc=0x1045bbc48]

goroutine 7 [running]:
maunium.net/go/mautrix.(*Client).SyncWithContext(0x140001302c0, {0x104cf3518, 0x105188920})
        /Users/ci/go/pkg/mod/maunium.net/go/mautrix@v0.16.0/client.go:176 +0x78
maunium.net/go/mautrix.(*Client).Sync(...)
        /Users/ci/go/pkg/mod/maunium.net/go/mautrix@v0.16.0/client.go:168
main.(*User).startSyncing.func1()
        /Users/ci/builds/YUMeaPfZ/0/mautrix/imessage/custompuppet.go:159 +0x3c
created by main.(*User).startSyncing in goroutine 1
        /Users/ci/builds/YUMeaPfZ/0/mautrix/imessage/custompuppet.go:158 +0x178

Things I tried:

Enabling ephemeral_events
Clearing my database
Trying a different platform (I was using bluebubbles, tried mac)

I'm running mautrix-imessage v0.1.0+dev.ea7aebde on Synapse v1.101.0.

I'll attach my full log and config:

PS: This is super low-pri for me, more of a curiosity more than anything but I thought ya'll might want to know. Thanks for all the hard work! Cheers!

mautrix / imessage

Panic when `sync_with_custom_puppets` is enabled #198