Panic in indexer logs while running GSI performance tests

2019-05-05T01:15:28.903-07:00 [Info] MutationStreamReader::updateSnapInFilter Huge Snapshot Received for bucket-1 947 MAINT_STREAM 0-311222

2019-05-05T01:15:28.923-07:00 [Fatal] IndexScanSource - panic detected while processing defnId:8372306296378590400, instId:18206720063615470450, index:bucket-1/myindex3, type:scan, partitions:[0], scans: <ud>([{["000015"] ["000028"] 3 range [] <nil>}])</ud>, consistency:any_consistency, requestId:./cbindexperf190542923

panic: runtime error: invalid memory address or nil pointer dereference [recovered]

        panic: runtime error: invalid memory address or nil pointer dereference

[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0xafed76]

goroutine 14933483 [running]:

panic(0xf3b000, 0xc420016080)

        /home/couchbase/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/panic.go:500 +0x1a1

github.com/couchbase/indexing/secondary/indexer.(*IndexScanSource).Routine.func1(0xc51a113c70)

        goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline.go:133 +0xcf

panic(0xf3b000, 0xc420016080)

        /home/couchbase/.cbdepscache/exploded/x86_64/go-1.7.6/go/src/runtime/panic.go:458 +0x243

github.com/couchbase/plasma.(*Iterator).Get(0xc42543d140, 0x0)

        goproj/src/github.com/couchbase/plasma/iterator.go:150 +0x26

github.com/couchbase/plasma.(*MVCCIterator).Key(0xc42ac2f8c0, 0xc42826d7f8, 0xaff03d, 0xc516b68f80)

        goproj/src/github.com/couchbase/plasma/mvcc.go:232 +0x2f

github.com/couchbase/plasma.(*MVCCIterator).refresh(0xc42ac2f8c0)

        goproj/src/github.com/couchbase/plasma/mvcc.go:191 +0x2f

github.com/couchbase/plasma.(*MVCCIterator).refreshIfNecessary(0xc42ac2f8c0)

        goproj/src/github.com/couchbase/plasma/mvcc.go:208 +0x58

github.com/couchbase/plasma.(*MVCCIterator).Next(0xc42ac2f8c0, 0x28, 0x28)

        goproj/src/github.com/couchbase/plasma/mvcc.go:216 +0x58

github.com/couchbase/indexing/secondary/indexer.(*plasmaSnapshot).Iterate(0xc50738e460, 0x1a63220, 0xc49ab149c0, 0x1a676c0, 0xc49ab14a00, 0x1a676c0, 0xc49ab14a40, 0x3, 0x11a2510, 0xc503027d40, ...)

        goproj/src/github.com/couchbase/indexing/secondary/indexer/plasma_slice.go:2093 +0x322

github.com/couchbase/indexing/secondary/indexer.(*plasmaSnapshot).Range(0xc50738e460, 0x1a63220, 0xc49ab149c0, 0x1a676c0, 0xc49ab14a00, 0x1a676c0, 0xc49ab14a40, 0x3, 0xc503027d40, 0xc42826db01, ...)

        goproj/src/github.com/couchbase/indexing/secondary/indexer/plasma_slice.go:2030 +0xb2

github.com/couchbase/indexing/secondary/indexer.scanSingleSlice(0xc517f53900, 0x1a676c0, 0xc49ab14a00, 0x1a676c0, 0xc49ab14a40, 0x3, 0x10af94a, 0x5, 0x0, 0x0, ...)

        goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_scatter.go:206 +0x41b

github.com/couchbase/indexing/secondary/indexer.scanOne(0xc517f53900, 0x1a676c0, 0xc49ab14a00, 0x1a676c0, 0xc49ab14a40, 0x3, 0x10af94a, 0x5, 0x0, 0x0, ...)

        goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_scatter.go:148 +0x11e

github.com/couchbase/indexing/secondary/indexer.scatter(0xc517f53900, 0x1a676c0, 0xc49ab14a00, 0x1a676c0, 0xc49ab14a40, 0x3, 0x10af94a, 0x5, 0x0, 0x0, ...)

        goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_scatter.go:55 +0xc6

github.com/couchbase/indexing/secondary/indexer.(*IndexScanSource).Routine(0xc51a113c70, 0x0, 0x0)

        goproj/src/github.com/couchbase/indexing/secondary/indexer/scan_pipeline.go:336 +0x810

github.com/couchbase/indexing/secondary/pipeline.(*Pipeline).runIt.func1(0xc49ab14a60, 0xc5032b6850)

        goproj/src/github.com/couchbase/indexing/secondary/pipeline/pipeline.go:75 +0x45

created by github.com/couchbase/indexing/secondary/pipeline.(*Pipeline).runIt

        goproj/src/github.com/couchbase/indexing/secondary/pipeline/pipeline.go:80 +0x66