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

goroutine 152047 [running]:
DIAGNOSIS:
I0303 10:22:35.596315   29274 main.go:305] ***************************
I0303 10:22:35.596453   29274 main.go:306] Args: [/syzkaller/managers/ptrace-proxy-sandbox-race/current/image -root /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root -watchdog-action=panic -network=none -debug -alsologtostderr -platform=ptrace -file-access=shared -network=sandbox -TESTONLY-unsafe-nonroot debug -stacks --ps ci-gvisor-ptrace-proxy-sandbox-race-3]
I0303 10:22:35.596713   29274 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0303 10:22:35.596811   29274 main.go:308] PID: 29274
I0303 10:22:35.596952   29274 main.go:309] UID: 0, GID: 0
I0303 10:22:35.597050   29274 main.go:310] Configuration:
I0303 10:22:35.597183   29274 main.go:311] 		RootDir: /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root
I0303 10:22:35.597278   29274 main.go:312] 		Platform: ptrace
I0303 10:22:35.597378   29274 main.go:313] 		FileAccess: shared, overlay: false
I0303 10:22:35.597530   29274 main.go:314] 		Network: sandbox, logging: false
I0303 10:22:35.597635   29274 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0303 10:22:35.597797   29274 main.go:316] ***************************
W0303 10:22:35.597924   29274 main.go:321] Block the TERM signal. This is only safe in tests!
D0303 10:22:35.598129   29274 container.go:159] Load container "/syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root" "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0303 10:22:35.607596   29274 container.go:592] Signal container "ci-gvisor-ptrace-proxy-sandbox-race-3": signal 0
D0303 10:22:35.607727   29274 sandbox.go:806] Signal sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0303 10:22:35.607824   29274 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0303 10:22:35.608397   29274 urpc.go:534] urpc: successfully marshalled 117 bytes.
I0303 10:22:36.118670   29274 debug.go:122] Found sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3", PID: 15613
I0303 10:22:36.118822   29274 debug.go:131] Retrieving sandbox stacks
D0303 10:22:36.118903   29274 sandbox.go:924] Stacks sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0303 10:22:36.119006   29274 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
W0303 10:22:36.119191   29274 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 15613: connection refused
retrieving stacks: connecting to control server at PID 15613: connection refused
W0303 10:22:36.119507   29274 main.go:338] Failure to execute command, err: 1