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

goroutine 3532702 [running]:
DIAGNOSIS:
I0304 16:57:51.916659   32923 main.go:305] ***************************
I0304 16:57:51.916727   32923 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-1]
I0304 16:57:51.916781   32923 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0304 16:57:51.916808   32923 main.go:308] PID: 32923
I0304 16:57:51.916837   32923 main.go:309] UID: 0, GID: 0
I0304 16:57:51.916870   32923 main.go:310] Configuration:
I0304 16:57:51.916906   32923 main.go:311] 		RootDir: /syzkaller/managers/main/workdir/gvisor_root
I0304 16:57:51.916951   32923 main.go:312] 		Platform: ptrace
I0304 16:57:51.916978   32923 main.go:313] 		FileAccess: shared, overlay: false
I0304 16:57:51.917019   32923 main.go:314] 		Network: none, logging: false
I0304 16:57:51.917052   32923 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0304 16:57:51.917088   32923 main.go:316] ***************************
D0304 16:57:51.917364   32923 container.go:159] Load container "/syzkaller/managers/main/workdir/gvisor_root" "ci-gvisor-main-1"
D0304 16:57:51.919351   32923 container.go:592] Signal container "ci-gvisor-main-1": signal 0
D0304 16:57:51.919399   32923 sandbox.go:806] Signal sandbox "ci-gvisor-main-1"
D0304 16:57:51.919415   32923 sandbox.go:318] Connecting to sandbox "ci-gvisor-main-1"
D0304 16:57:51.919572   32923 urpc.go:534] urpc: successfully marshalled 96 bytes.
I0304 16:57:53.308856   32923 debug.go:122] Found sandbox "ci-gvisor-main-1", PID: 61052
I0304 16:57:53.308955   32923 debug.go:131] Retrieving sandbox stacks
D0304 16:57:53.308985   32923 sandbox.go:924] Stacks sandbox "ci-gvisor-main-1"
D0304 16:57:53.309000   32923 sandbox.go:318] Connecting to sandbox "ci-gvisor-main-1"
W0304 16:57:53.309051   32923 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 61052: connection refused
retrieving stacks: connecting to control server at PID 61052: connection refused
W0304 16:57:53.309267   32923 main.go:338] Failure to execute command, err: 1