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

goroutine 317358 [running]:
DIAGNOSIS:
I0304 20:10:21.550690    9964 main.go:305] ***************************
I0304 20:10:21.550866    9964 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-0]
I0304 20:10:21.551088    9964 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0304 20:10:21.551242    9964 main.go:308] PID: 9964
I0304 20:10:21.551361    9964 main.go:309] UID: 0, GID: 0
I0304 20:10:21.551488    9964 main.go:310] Configuration:
I0304 20:10:21.551587    9964 main.go:311] 		RootDir: /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root
I0304 20:10:21.551695    9964 main.go:312] 		Platform: ptrace
I0304 20:10:21.551819    9964 main.go:313] 		FileAccess: shared, overlay: false
I0304 20:10:21.551940    9964 main.go:314] 		Network: sandbox, logging: false
I0304 20:10:21.552055    9964 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0304 20:10:21.552210    9964 main.go:316] ***************************
W0304 20:10:21.552297    9964 main.go:321] Block the TERM signal. This is only safe in tests!
D0304 20:10:21.552543    9964 container.go:159] Load container "/syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root" "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0304 20:10:21.559762    9964 container.go:592] Signal container "ci-gvisor-ptrace-proxy-sandbox-race-0": signal 0
D0304 20:10:21.559969    9964 sandbox.go:806] Signal sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0304 20:10:21.560101    9964 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0304 20:10:21.560710    9964 urpc.go:534] urpc: successfully marshalled 117 bytes.
I0304 20:10:22.247825    9964 debug.go:122] Found sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0", PID: 61122
I0304 20:10:22.248001    9964 debug.go:131] Retrieving sandbox stacks
D0304 20:10:22.248098    9964 sandbox.go:924] Stacks sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0304 20:10:22.248220    9964 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
W0304 20:10:22.248460    9964 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 61122: connection refused
retrieving stacks: connecting to control server at PID 61122: connection refused
W0304 20:10:22.248939    9964 main.go:338] Failure to execute command, err: 1