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

goroutine 342 [running]:
DIAGNOSIS:
I0301 13:49:56.062770   26614 main.go:305] ***************************
I0301 13:49:56.062910   26614 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-2]
I0301 13:49:56.063106   26614 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0301 13:49:56.063214   26614 main.go:308] PID: 26614
I0301 13:49:56.063328   26614 main.go:309] UID: 0, GID: 0
I0301 13:49:56.063406   26614 main.go:310] Configuration:
I0301 13:49:56.063479   26614 main.go:311] 		RootDir: /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root
I0301 13:49:56.063557   26614 main.go:312] 		Platform: ptrace
I0301 13:49:56.063657   26614 main.go:313] 		FileAccess: shared, overlay: false
I0301 13:49:56.063797   26614 main.go:314] 		Network: sandbox, logging: false
I0301 13:49:56.063912   26614 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0301 13:49:56.064011   26614 main.go:316] ***************************
W0301 13:49:56.064076   26614 main.go:321] Block the TERM signal. This is only safe in tests!
D0301 13:49:56.064279   26614 container.go:159] Load container "/syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root" "ci-gvisor-ptrace-proxy-sandbox-race-2"
D0301 13:49:56.071727   26614 container.go:592] Signal container "ci-gvisor-ptrace-proxy-sandbox-race-2": signal 0
D0301 13:49:56.071916   26614 sandbox.go:806] Signal sandbox "ci-gvisor-ptrace-proxy-sandbox-race-2"
D0301 13:49:56.072012   26614 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-2"
D0301 13:49:56.072433   26614 urpc.go:534] urpc: successfully marshalled 117 bytes.
I0301 13:49:56.196874   26614 debug.go:122] Found sandbox "ci-gvisor-ptrace-proxy-sandbox-race-2", PID: 21242
I0301 13:49:56.197834   26614 debug.go:131] Retrieving sandbox stacks
D0301 13:49:56.197956   26614 sandbox.go:924] Stacks sandbox "ci-gvisor-ptrace-proxy-sandbox-race-2"
D0301 13:49:56.198068   26614 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-2"
W0301 13:49:56.198241   26614 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 21242: connection refused
retrieving stacks: connecting to control server at PID 21242: connection refused
W0301 13:49:56.198610   26614 main.go:338] Failure to execute command, err: 1