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

goroutine 737072 [running]:
DIAGNOSIS:
I0304 08:04:44.609658   21291 main.go:305] ***************************
I0304 08:04:44.609771   21291 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-1]
I0304 08:04:44.609938   21291 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0304 08:04:44.609993   21291 main.go:308] PID: 21291
I0304 08:04:44.610069   21291 main.go:309] UID: 0, GID: 0
I0304 08:04:44.610136   21291 main.go:310] Configuration:
I0304 08:04:44.610218   21291 main.go:311] 		RootDir: /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root
I0304 08:04:44.610298   21291 main.go:312] 		Platform: ptrace
I0304 08:04:44.610360   21291 main.go:313] 		FileAccess: shared, overlay: false
I0304 08:04:44.610458   21291 main.go:314] 		Network: sandbox, logging: false
I0304 08:04:44.610547   21291 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0304 08:04:44.610632   21291 main.go:316] ***************************
W0304 08:04:44.610703   21291 main.go:321] Block the TERM signal. This is only safe in tests!
D0304 08:04:44.610897   21291 container.go:159] Load container "/syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root" "ci-gvisor-ptrace-proxy-sandbox-race-1"
D0304 08:04:44.616811   21291 container.go:592] Signal container "ci-gvisor-ptrace-proxy-sandbox-race-1": signal 0
D0304 08:04:44.616960   21291 sandbox.go:806] Signal sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1"
D0304 08:04:44.617099   21291 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1"
D0304 08:04:44.617524   21291 urpc.go:534] urpc: successfully marshalled 117 bytes.
I0304 08:04:45.252261   21291 debug.go:122] Found sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1", PID: 65036
I0304 08:04:45.252499   21291 debug.go:131] Retrieving sandbox stacks
D0304 08:04:45.252637   21291 sandbox.go:924] Stacks sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1"
D0304 08:04:45.252772   21291 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1"
W0304 08:04:45.252965   21291 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 65036: connection refused
retrieving stacks: connecting to control server at PID 65036: connection refused
W0304 08:04:45.253379   21291 main.go:338] Failure to execute command, err: 1