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

goroutine 127728 [running]:
DIAGNOSIS:
I0304 21:25:41.572053   32817 main.go:305] ***************************
I0304 21:25:41.572239   32817 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 21:25:41.572454   32817 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0304 21:25:41.572565   32817 main.go:308] PID: 32817
I0304 21:25:41.572695   32817 main.go:309] UID: 0, GID: 0
I0304 21:25:41.572819   32817 main.go:310] Configuration:
I0304 21:25:41.572930   32817 main.go:311] 		RootDir: /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root
I0304 21:25:41.573054   32817 main.go:312] 		Platform: ptrace
I0304 21:25:41.573154   32817 main.go:313] 		FileAccess: shared, overlay: false
I0304 21:25:41.573285   32817 main.go:314] 		Network: sandbox, logging: false
I0304 21:25:41.573394   32817 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0304 21:25:41.573493   32817 main.go:316] ***************************
W0304 21:25:41.573628   32817 main.go:321] Block the TERM signal. This is only safe in tests!
D0304 21:25:41.573914   32817 container.go:159] Load container "/syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root" "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0304 21:25:41.581851   32817 container.go:592] Signal container "ci-gvisor-ptrace-proxy-sandbox-race-0": signal 0
D0304 21:25:41.582017   32817 sandbox.go:806] Signal sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0304 21:25:41.582150   32817 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0304 21:25:41.582711   32817 urpc.go:534] urpc: successfully marshalled 117 bytes.
I0304 21:25:42.047831   32817 debug.go:122] Found sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0", PID: 26760
I0304 21:25:42.048008   32817 debug.go:131] Retrieving sandbox stacks
D0304 21:25:42.048095   32817 sandbox.go:924] Stacks sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0304 21:25:42.048433   32817 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
W0304 21:25:42.048643   32817 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 26760: connection refused
retrieving stacks: connecting to control server at PID 26760: connection refused
W0304 21:25:42.049070   32817 main.go:338] Failure to execute command, err: 1