panic: runtime error: index out of range [271] with length 0

goroutine 51 [running]:
compress/flate.(*huffmanBitWriter).indexTokens(0xc0002e85a0, {0xc0003a0000, 0x8, 0xc0005558e8?})
	/usr/local/go/src/compress/flate/huffman_bit_writer.go:547 +0x2bd
compress/flate.(*huffmanBitWriter).writeBlock(0xc0002e85a0, {0xc0003a0000?, 0x1000?, 0xd?}, 0x0, {0xc000398572, 0x2f, 0x7a8e})
	/usr/local/go/src/compress/flate/huffman_bit_writer.go:437 +0xbe
compress/flate.(*compressor).writeBlock(0xc0005c0000, {0xc0003a0000?, 0x9c9c38?, 0x67cd4a?}, 0xd9b760?)
	/usr/local/go/src/compress/flate/deflate.go:170 +0x9d
compress/flate.(*compressor).deflate(0xc0005c0000)
	/usr/local/go/src/compress/flate/deflate.go:408 +0x618
compress/flate.(*compressor).syncFlush(0xc0005c0000)
	/usr/local/go/src/compress/flate/deflate.go:558 +0x3b
compress/flate.(*Writer).Flush(...)
	/usr/local/go/src/compress/flate/deflate.go:725
github.com/google/syzkaller/pkg/rpctype.(*flateConn).Write(0xc0004fcc60, {0xc000358000?, 0xa95300?, 0xc0007a2120?})
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/rpctype/rpc.go:132 +0x45
bufio.(*Writer).Flush(0xc00048dec0)
	/usr/local/go/src/bufio/bufio.go:639 +0x55
net/rpc.(*gobClientCodec).WriteRequest(0xc0004fcd50, 0xc0004fcd80?, {0xa95300, 0xc0007a2120})
	/usr/local/go/src/net/rpc/client.go:224 +0x6c
net/rpc.(*Client).send(0xc0000afd40, 0xc0007f2230)
	/usr/local/go/src/net/rpc/client.go:91 +0x224
net/rpc.(*Client).Go(0xc0000afd40, {0xc2b58b, 0x16}, {0xa95300, 0xc0007a2120}, {0x0, 0x0}, 0x0)
	/usr/local/go/src/net/rpc/client.go:315 +0x13a
github.com/google/syzkaller/pkg/rpctype.(*RPCClient).AsyncCall(...)
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/rpctype/rpc.go:92
main.(*FuzzerTool).startExecutingCall(...)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:268
main.(*Proc).executeProgram(0xc0000a26d8, {0xaee, {0xc0007a1b00, 0x448, 0x448}, {0x15, 0x4762, 0x0}, 0x1, 0x0, ...})
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:121 +0x12a
main.(*Proc).execute(0xc0000a26d8?, {0xaee, {0xc0007a1b00, 0x448, 0x448}, {0x15, 0x4762, 0x0}, 0x1, 0x0, ...})
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:99 +0x98
main.(*Proc).loop(0xc0000a26d8)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:50 +0x278
created by main.startProc in goroutine 1
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:37 +0x10a
panic: runtime error: index out of range [271] with length 0

goroutine 56 [running]:
compress/flate.(*huffmanBitWriter).indexTokens(0xc0002e85a0, {0xc0003a0000, 0x8, 0xc0000df8f8?})
	/usr/local/go/src/compress/flate/huffman_bit_writer.go:547 +0x2bd
compress/flate.(*huffmanBitWriter).writeBlock(0xc0002e85a0, {0xc0003a0000?, 0x407ecb?, 0xc0000df998?}, 0x0, {0xc0003985a1, 0x0, 0x7a5f})
	/usr/local/go/src/compress/flate/huffman_bit_writer.go:437 +0xbe
compress/flate.(*compressor).writeBlock(0xc0005c0000, {0xc0003a0000?, 0x9c8800?, 0xc00049f210?}, 0xc000a7c000?)
	/usr/local/go/src/compress/flate/deflate.go:170 +0x9d
compress/flate.(*compressor).deflate(0xc0005c0000)
	/usr/local/go/src/compress/flate/deflate.go:408 +0x618
compress/flate.(*compressor).write(0xc0005c0000, {0xc000358000?, 0x60, 0xa95300?})
	/usr/local/go/src/compress/flate/deflate.go:544 +0x72
compress/flate.(*Writer).Write(...)
	/usr/local/go/src/compress/flate/deflate.go:710
github.com/google/syzkaller/pkg/rpctype.(*flateConn).Write(0xc0004fcc60, {0xc000358000?, 0xa95300?, 0xc0006ea150?})
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/rpctype/rpc.go:128 +0x26
bufio.(*Writer).Flush(0xc00048dec0)
	/usr/local/go/src/bufio/bufio.go:639 +0x55
net/rpc.(*gobClientCodec).WriteRequest(0xc0004fcd50, 0xc0004fcd80?, {0xa95300, 0xc0006ea150})
	/usr/local/go/src/net/rpc/client.go:224 +0x6c
net/rpc.(*Client).send(0xc0000afd40, 0xc0008da460)
	/usr/local/go/src/net/rpc/client.go:91 +0x224
net/rpc.(*Client).Go(0xc0000afd40, {0xc2b58b, 0x16}, {0xa95300, 0xc0006ea150}, {0x0, 0x0}, 0x0)
	/usr/local/go/src/net/rpc/client.go:315 +0x13a
github.com/google/syzkaller/pkg/rpctype.(*RPCClient).AsyncCall(...)
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/rpctype/rpc.go:92
main.(*FuzzerTool).startExecutingCall(...)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:268
main.(*Proc).executeProgram(0xc0000a2750, {0xaf0, {0xc0008c2500, 0x4da, 0x4da}, {0x14, 0x4762, 0x0}, 0x0, 0x0, ...})
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:121 +0x12a
main.(*Proc).execute(0xc0000a2750?, {0xaf0, {0xc0008c2500, 0x4da, 0x4da}, {0x14, 0x4762, 0x0}, 0x0, 0x0, ...})
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:99 +0x98
main.(*Proc).loop(0xc0000a2750)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:50 +0x278
created by main.startProc in goroutine 1
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:37 +0x10a