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

goroutine 1248868 [running]:
DIAGNOSIS:
I0304 15:30:17.768853   30440 main.go:305] ***************************
I0304 15:30:17.769001   30440 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 15:30:17.769222   30440 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0304 15:30:17.769357   30440 main.go:308] PID: 30440
I0304 15:30:17.769474   30440 main.go:309] UID: 0, GID: 0
I0304 15:30:17.769572   30440 main.go:310] Configuration:
I0304 15:30:17.769679   30440 main.go:311] 		RootDir: /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root
I0304 15:30:17.769791   30440 main.go:312] 		Platform: ptrace
I0304 15:30:17.769866   30440 main.go:313] 		FileAccess: shared, overlay: false
I0304 15:30:17.769981   30440 main.go:314] 		Network: sandbox, logging: false
I0304 15:30:17.770068   30440 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0304 15:30:17.770130   30440 main.go:316] ***************************
W0304 15:30:17.770182   30440 main.go:321] Block the TERM signal. This is only safe in tests!
D0304 15:30:17.770470   30440 container.go:159] Load container "/syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root" "ci-gvisor-ptrace-proxy-sandbox-race-1"
D0304 15:30:17.781719   30440 container.go:592] Signal container "ci-gvisor-ptrace-proxy-sandbox-race-1": signal 0
D0304 15:30:17.781923   30440 sandbox.go:806] Signal sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1"
D0304 15:30:17.782087   30440 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1"
D0304 15:30:17.782742   30440 urpc.go:534] urpc: successfully marshalled 117 bytes.
I0304 15:30:18.665224   30440 debug.go:122] Found sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1", PID: 15074
I0304 15:30:18.665473   30440 debug.go:131] Retrieving sandbox stacks
D0304 15:30:18.665616   30440 sandbox.go:924] Stacks sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1"
D0304 15:30:18.665742   30440 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-1"
W0304 15:30:18.665924   30440 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 15074: connection refused
retrieving stacks: connecting to control server at PID 15074: connection refused
W0304 15:30:18.666288   30440 main.go:338] Failure to execute command, err: 1