panic: runtime error: index out of range [1] with length 0

goroutine 4072733 [running]:
DIAGNOSIS:
I0304 12:39:59.928559   35722 main.go:305] ***************************
I0304 12:39:59.928618   35722 main.go:306] Args: [/syzkaller/managers/main/current/image -root /syzkaller/managers/main/workdir/gvisor_root -watchdog-action=panic -network=none -debug -alsologtostderr -platform=ptrace -file-access=shared -network=none debug -stacks --ps ci-gvisor-main-3]
I0304 12:39:59.928681   35722 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0304 12:39:59.928707   35722 main.go:308] PID: 35722
I0304 12:39:59.928732   35722 main.go:309] UID: 0, GID: 0
I0304 12:39:59.928754   35722 main.go:310] Configuration:
I0304 12:39:59.928778   35722 main.go:311] 		RootDir: /syzkaller/managers/main/workdir/gvisor_root
I0304 12:39:59.928814   35722 main.go:312] 		Platform: ptrace
I0304 12:39:59.928844   35722 main.go:313] 		FileAccess: shared, overlay: false
I0304 12:39:59.928877   35722 main.go:314] 		Network: none, logging: false
I0304 12:39:59.928905   35722 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0304 12:39:59.928928   35722 main.go:316] ***************************
D0304 12:39:59.928999   35722 container.go:159] Load container "/syzkaller/managers/main/workdir/gvisor_root" "ci-gvisor-main-3"
D0304 12:39:59.930533   35722 container.go:592] Signal container "ci-gvisor-main-3": signal 0
D0304 12:39:59.930575   35722 sandbox.go:806] Signal sandbox "ci-gvisor-main-3"
D0304 12:39:59.930590   35722 sandbox.go:318] Connecting to sandbox "ci-gvisor-main-3"
D0304 12:39:59.930737   35722 urpc.go:534] urpc: successfully marshalled 96 bytes.
I0304 12:40:01.602686   35722 debug.go:122] Found sandbox "ci-gvisor-main-3", PID: 20603
I0304 12:40:01.602733   35722 debug.go:131] Retrieving sandbox stacks
D0304 12:40:01.602772   35722 sandbox.go:924] Stacks sandbox "ci-gvisor-main-3"
D0304 12:40:01.602787   35722 sandbox.go:318] Connecting to sandbox "ci-gvisor-main-3"
W0304 12:40:01.602834   35722 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 20603: connection refused
retrieving stacks: connecting to control server at PID 20603: connection refused
W0304 12:40:01.602987   35722 main.go:338] Failure to execute command, err: 1