Message edits on Matrix side fail to propagate to Slack

Steps to reproduce 1. Mautrix-slack in relaybot mode. 2. Post a message from non-logged-in matrix user 3. Edit posted message 4. An error message is shown in the room  Mautrix-slack logs follow: ``` Feb 21 23:50:29 morpheus mautrix-slack[1765522]: 2025-02-21T23:50:29.734+02:00 ERR Event handling panicked error="runtime error: invalid memory address or nil pointer dereference" action="handle matrix event" event_id=$Yfk6V2Bh1IXhQ_0Aj7jRO99K00I25ECG7 dlxPW1Islk event_loop_index=20 event_type=m.room.message portal_id=T4VQB4VAM-C5K4S3JKE portal_mxid=!HxolHJbvlHAPuDmDND:hacklab.fi sender=@zouppen:hacklab.fi stack="goroutine 636 [running]:\nruntime/debug.Stack()\n\t/opt/mautrix-slack/go/pkg/mod/golang. org/toolchain@v0.0.1-go1.23.4.linux-amd64/src/runtime/debug/stack.go:26 +0x5e\nmaunium.net/go/mautrix/bridgev2.(*Portal).handleSingleEvent.func1()\n\t/opt/mautrix-slack/go/pkg/mod/maunium.net/go/mautrix@v0.22.2-0.20250110154103-bbcb1904e268/bridgev2/po rtal.go:375 +0xf4\npanic({0xec21e0?, 0x1718020?})\n\t/opt/mautrix-slack/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.23.4.linux-amd64/src/runtime/panic.go:785 +0x132\nmaunium.net/go/mautrix/bridgev2.(*Portal).handleMatrixEdit(0xc0006f0690, {0x118f3f0, 0xc000c429f0}, 0xc0006e6540, 0xc00087c6e0, 0xc000cb9340, 0xc000bb7a20, 0x172aa40)\n\t/opt/mautrix-slack/go/pkg/mod/maunium.net/go/mautrix@v0.22.2-0.20250110154103-bbcb1904e268/bridgev2/portal.go:1096 +0x328\nmaunium.net/go/mautrix/bridgev2.(*Portal).handleMatrixMessage(0xc0006f0690, {0x118f3f0, 0xc000c429f0}, 0xc0006e6540, 0xc00087c6e0, 0xc000cb9340)\n\t/opt/mautrix-slack/go/pkg/mod/maunium.net/go/mautrix@v0.22.2-0.20250110154103-bbcb1904e268/bridgev2/portal.go:828 +0x653\nmaunium.net/go/mautrix/bridgev2.(*Portal).handleMatrixEvent(0xc0006f0690, {0x118f3f0, 0xc000c428d0}, 0xc0005ba000, 0xc000cb9340)\n\t/opt/mautrix-slack/go/pkg/mod/maunium.net/go/mautrix@v0.22.2-0.20250110154103-bbcb1904e268/bridgev2/portal.go:541 +0x985\nmaunium.net/go/mautrix/bridgev2.(*Portal).handleSingleEvent(0xc0006f0690, {0x118f3f0, 0xc000c428d0}, {0xea2420, 0xc000595010}, 0xc000d405c0)\n\t/opt/mautrix-slack/go/pkg/mod/maunium.net/go/mautrix@v0.22.2-0.20250110154103-bbcb1904e268/bridgev2/portal.go:389 +0x151\ncreated by maunium.net/go/mautrix/bridgev2.(*Portal).handleSingleEventAsync in goroutine 570\n\t/opt/mautrix-slack/go/pkg/mod/maunium.net/go/mautrix@v0.22.2-0.20250110154103-bbcb1904e268/bridgev2/portal.go:310 +0x267\n" Feb 21 23:50:29 morpheus mautrix-slack[1765522]: 2025-02-21T23:50:29.769+02:00 DBG Starting handling of transaction content={"pdu":0,"unstable_edu":1,"unstable_to_device":0} transaction_id=122236680 Feb 21 23:50:29 morpheus mautrix-slack[1765522]: 2025-02-21T23:50:29.769+02:00 DBG Finished dispatching events from transaction transaction_id=122236680 Feb 21 23:50:29 morpheus mautrix-slack[1765522]: 2025-02-21T23:50:29.783+02:00 DBG Request completed action="handle matrix event" duration=48.112797 event_id=$Yfk6V2Bh1IXhQ_0Aj7jRO99K00I25ECG7dlxPW1Islk event_loop_index=20 event_type=m.room.message method=PUT portal_id=T4VQB4VAM-C5K4S3JKE portal_mxid=!HxolHJbvlHAPuDmDND:hacklab.fi req_body={"body":"⚠ Your message may not have been bridged: panic in event handler","m.mentions":{"user_ids":["@zouppen:hacklab.fi"]},"m.relates_to":{"m.in_reply_to":{"event_id":"$Yfk6V2Bh1IXhQ_0Aj7jRO99K00I25ECG7dlxPW1Islk"}},"msgtype":"m.text"} req_id=419 response_length=59 response_mime=application/json sender=@zouppen:hacklab.fi status_code=200 url=http://localhost:8008/_matrix/client/v3/rooms/%21HxolHJbvlHAPuDmDND:hacklab.fi/send/m.room.message/mautrix-go_1740174629734991419_2?user_id=%40slackbot%3Ahacklab.fi ```