MRE: tap v0.1.4 nil pointer dereference (firehose.go:184)

tap_v0.1.4_nil_prevdata_mre.sh

#!/bin/bash
# MRE: tap v0.1.4 nil pointer dereference when evt.PrevData is nil
# Bug: firehose.go:184 calls evt.PrevData.String() without nil check
# https://github.com/bluesky-social/indigo/blob/tap-v0.1.4/cmd/tap/firehose.go#L184

set -e
dir=$(mktemp -d)
trap "rm -rf $dir" EXIT
cd "$dir"

cat > main.go << 'GO'
package main

import comatproto "github.com/bluesky-social/indigo/api/atproto"

func main() {
	// This is what firehose.go:184 does in tap v0.1.4
	evt := &comatproto.SyncSubscribeRepos_Commit{PrevData: nil}
	_ = evt.PrevData.String() // BOOM
}
GO

go mod init mre >/dev/null 2>&1
go get github.com/bluesky-social/indigo@tap-v0.1.4 >/dev/null 2>&1
go mod tidy >/dev/null 2>&1

echo "tap v0.1.4 nil PrevData MRE - expect crash:"
go run .