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

DIAGNOSIS:
I0305 17:25:10.633354   29034 main.go:305] ***************************
I0305 17:25:10.633522   29034 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]
I0305 17:25:10.633698   29034 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0305 17:25:10.633755   29034 main.go:308] PID: 29034
I0305 17:25:10.633824   29034 main.go:309] UID: 0, GID: 0
I0305 17:25:10.633974   29034 main.go:310] Configuration:
I0305 17:25:10.634068   29034 main.go:311] 		RootDir: /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root
I0305 17:25:10.634189   29034 main.go:312] 		Platform: ptrace
I0305 17:25:10.634300   29034 main.go:313] 		FileAccess: shared, overlay: false
I0305 17:25:10.634455   29034 main.go:314] 		Network: sandbox, logging: false
I0305 17:25:10.634623   29034 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0305 17:25:10.634717   29034 main.go:316] ***************************
W0305 17:25:10.634820   29034 main.go:321] Block the TERM signal. This is only safe in tests!
D0305 17:25:10.635431   29034 container.go:159] Load container "/syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root" "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0305 17:25:10.643186   29034 container.go:592] Signal container "ci-gvisor-ptrace-proxy-sandbox-race-3": signal 0
D0305 17:25:10.643393   29034 sandbox.go:806] Signal sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0305 17:25:10.643517   29034 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0305 17:25:10.644136   29034 urpc.go:534] urpc: successfully marshalled 117 bytes.
I0305 17:25:11.318795   29034 debug.go:122] Found sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3", PID: 16680
I0305 17:25:11.318953   29034 debug.go:131] Retrieving sandbox stacks
D0305 17:25:11.319158   29034 sandbox.go:924] Stacks sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
D0305 17:25:11.319448   29034 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-3"
W0305 17:25:11.319667   29034 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 16680: connection refused
retrieving stacks: connecting to control server at PID 16680: connection refused
W0305 17:25:11.320086   29034 main.go:338] Failure to execute command, err: 1