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

goroutine 4735490 [running]:
DIAGNOSIS:
I0303 15:44:34.255460   16420 main.go:305] ***************************
I0303 15:44:34.255547   16420 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-0]
I0303 15:44:34.255604   16420 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0303 15:44:34.255627   16420 main.go:308] PID: 16420
I0303 15:44:34.255650   16420 main.go:309] UID: 0, GID: 0
I0303 15:44:34.255674   16420 main.go:310] Configuration:
I0303 15:44:34.255694   16420 main.go:311] 		RootDir: /syzkaller/managers/main/workdir/gvisor_root
I0303 15:44:34.255730   16420 main.go:312] 		Platform: ptrace
I0303 15:44:34.255759   16420 main.go:313] 		FileAccess: shared, overlay: false
I0303 15:44:34.255789   16420 main.go:314] 		Network: none, logging: false
I0303 15:44:34.255812   16420 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0303 15:44:34.255833   16420 main.go:316] ***************************
D0303 15:44:34.261348   16420 container.go:159] Load container "/syzkaller/managers/main/workdir/gvisor_root" "ci-gvisor-main-0"
D0303 15:44:34.284776   16420 container.go:592] Signal container "ci-gvisor-main-0": signal 0
D0303 15:44:34.285035   16420 sandbox.go:806] Signal sandbox "ci-gvisor-main-0"
D0303 15:44:34.286761   16420 sandbox.go:318] Connecting to sandbox "ci-gvisor-main-0"
D0303 15:44:34.288038   16420 urpc.go:534] urpc: successfully marshalled 96 bytes.
I0303 15:44:36.040287   16420 debug.go:122] Found sandbox "ci-gvisor-main-0", PID: 7898
I0303 15:44:36.040325   16420 debug.go:131] Retrieving sandbox stacks
D0303 15:44:36.040382   16420 sandbox.go:924] Stacks sandbox "ci-gvisor-main-0"
D0303 15:44:36.040398   16420 sandbox.go:318] Connecting to sandbox "ci-gvisor-main-0"
W0303 15:44:36.040446   16420 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 7898: connection refused
retrieving stacks: connecting to control server at PID 7898: connection refused
W0303 15:44:36.040613   16420 main.go:338] Failure to execute command, err: 1