Panic in openonu-go during disable-enable ONU test

Panic in openonu-go during disable-enable ONU test in this job https://jenkins.opencord.org/view/Community-PODs/job/build_dt-berlin-pod-multi-olt_1T8GEM_voltha_DT_master_test.

Check run #140 for the logs. Logs also attached here.

Panic details :

voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]: panic: runtime error: invalid memory address or nil pointer dereference
voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]: [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xec920b]
voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]:
voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]: goroutine 41280 [running]:
voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]: github.com/opencord/voltha-openonu-adapter-go/internal/pkg/onuadaptercore.(*lockStateFsm).handleOmciLockStateMessage(0xc000c9a6e0, 0x14314c0, 0xc000cfeed0, 0xc0007349a0, 0xc000bf7f20)
voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]: /go/src/github.com/opencord/voltha-openonu-adapter-go/internal/pkg/onuadaptercore/uniportadmin.go:320 +0x32b
voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]: github.com/opencord/voltha-openonu-adapter-go/internal/pkg/onuadaptercore.(*lockStateFsm).processOmciLockMessages(0xc000c9a6e0, 0x14314c0, 0xc000cfeed0)
voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]: /go/src/github.com/opencord/voltha-openonu-adapter-go/internal/pkg/onuadaptercore/uniportadmin.go:287 +0x617
voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]: created by github.com/opencord/voltha-openonu-adapter-go/internal/pkg/onuadaptercore.(*lockStateFsm).enterAdminStartingState
voltha/open-onu-voltha-adapter-openonu-5fc846b8b5-sq78c[adapter-open-onu]: /go/src/github.com/opencord/voltha-openonu-adapter-go/internal/pkg/onuadaptercore/uniportadmin.go:183 +0x1e4