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

goroutine 1622431 [running]:
DIAGNOSIS:
I0305 00:26:00.915982   20930 main.go:305] ***************************
I0305 00:26:00.916101   20930 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]
I0305 00:26:00.916281   20930 main.go:307] Version release-20200219.0-72-gce4d1e45bb88
I0305 00:26:00.916351   20930 main.go:308] PID: 20930
I0305 00:26:00.916453   20930 main.go:309] UID: 0, GID: 0
I0305 00:26:00.916592   20930 main.go:310] Configuration:
I0305 00:26:00.916660   20930 main.go:311] 		RootDir: /syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root
I0305 00:26:00.916732   20930 main.go:312] 		Platform: ptrace
I0305 00:26:00.916796   20930 main.go:313] 		FileAccess: shared, overlay: false
I0305 00:26:00.916889   20930 main.go:314] 		Network: sandbox, logging: false
I0305 00:26:00.916953   20930 main.go:315] 		Strace: false, max size: 1024, syscalls: []
I0305 00:26:00.917021   20930 main.go:316] ***************************
W0305 00:26:00.917083   20930 main.go:321] Block the TERM signal. This is only safe in tests!
D0305 00:26:00.917296   20930 container.go:159] Load container "/syzkaller/managers/ptrace-proxy-sandbox-race/workdir/gvisor_root" "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0305 00:26:00.925769   20930 container.go:592] Signal container "ci-gvisor-ptrace-proxy-sandbox-race-0": signal 0
D0305 00:26:00.925976   20930 sandbox.go:806] Signal sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0305 00:26:00.926093   20930 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0305 00:26:00.926866   20930 urpc.go:534] urpc: successfully marshalled 117 bytes.
I0305 00:26:02.143683   20930 debug.go:122] Found sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0", PID: 54370
I0305 00:26:02.143845   20930 debug.go:131] Retrieving sandbox stacks
D0305 00:26:02.143958   20930 sandbox.go:924] Stacks sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
D0305 00:26:02.144109   20930 sandbox.go:318] Connecting to sandbox "ci-gvisor-ptrace-proxy-sandbox-race-0"
W0305 00:26:02.144293   20930 error.go:48] FATAL ERROR: retrieving stacks: connecting to control server at PID 54370: connection refused
retrieving stacks: connecting to control server at PID 54370: connection refused
W0305 00:26:02.144706   20930 main.go:338] Failure to execute command, err: 1