index out of range panic

[KaniuBillows]

Unable to reproduce through unit test for the time being, but it does exist in my application. I write a batch of documents to bluge through Batch, then query them and delete them. Then write new documents, keep looping. My program seems to crash randomly.

panic: runtime error: index out of range [559] with length 4

goroutine 13220 [running]:
github.com/blugelabs/bluge/index.(*segmentMerge).ProcessSegmentNow(0xc01e152330, 0xc001cf5108?, 0xc01a97c120, 0xc013d49cd8?)
	/root/go/pkg/mod/github.com/seafileltd/[email protected]/index/merge.go:272 +0x11c
github.com/blugelabs/bluge/index.(*Writer).introduceMerge(0xc002086480, 0xc01e152330, 0x66)
	/root/go/pkg/mod/github.com/seafileltd/[email protected]/index/introducer.go:261 +0x1e5
github.com/blugelabs/bluge/index.(*Writer).introducerLoop(0xc002086480, 0xc001c85800, 0xc001c858c0, 0xc001c85980, 0xc00bf50300, 0xc000482f98?)
	/root/go/pkg/mod/github.com/seafileltd/[email protected]/index/introducer.go:61 +0x24f
created by github.com/blugelabs/bluge/index.OpenWriter in goroutine 13055
	/root/go/pkg/mod/github.com/seafileltd/[email protected]/index/writer.go:127 +0x6b8

After reading the code, I found that this is related to cleaning up the old document when merging the segments, but I passed the unit test and failed to reproduce it. I really don't understand why it is accessed out of bounds, which may be related to the maintenance of bitmap?