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

goroutine 1750872 [running]:
DIAGNOSIS:
I0304 06:54:27.142388   38650 main.go:305] ***************************
I0304 06:54:27.142536   38650 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]
I0304 06:54:27.142671   38650 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0304 06:54:27.142750   38650 main.go:308] PID: 38650
I0304 06:54:27.142822   38650 main.go:309] UID: 0, GID: 0
I0304 06:54:27.142887   38650 main.go:310] Configuration:
I0304 06:54:27.142942   38650 main.go:311] 		RootDir: /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root
I0304 06:54:27.142997   38650 main.go:312] 		Platform: ptrace
I0304 06:54:27.143070   38650 main.go:313] 		FileAccess: shared, overlay: false
I0304 06:54:27.143149   38650 main.go:314] 		Network: sandbox, logging: false
I0304 06:54:27.143211   38650 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0304 06:54:27.143284   38650 main.go:316] ***************************
W0304 06:54:27.143354   38650 main.go:321] Block the TERM signal. This is only safe in tests!
D0304 06:54:27.143830   38650 container.go:159] Load container "/syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root" "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0304 06:54:27.149279   38650 container.go:592] Signal container "ci-gvisor-ptrace-proxy-sandbox-race-3": signal 0
D0304 06:54:27.149402   38650 sandbox.go:806] Signal sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0304 06:54:27.149476   38650 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0304 06:54:27.149906   38650 urpc.go:534] urpc: successfully marshalled 117 bytes.
I0304 06:54:28.382051   38650 debug.go:122] Found sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3", PID: 64347
I0304 06:54:28.382218   38650 debug.go:131] Retrieving sandbox stacks
D0304 06:54:28.382359   38650 sandbox.go:924] Stacks sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0304 06:54:28.382533   38650 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
W0304 06:54:28.382788   38650 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 64347: connection refused
retrieving stacks: connecting to control server at PID 64347: connection refused
W0304 06:54:28.383244   38650 main.go:338] Failure to execute command, err: 1