Fixed NPE caused by trying to close the browser before it is initialised
Fixed NPE caused by trying to close the browser before it is initialised

gaieepo/HubTurbo,saav/HubTurbo,Sumei1009/HubTurbo,ianngiaw/HubTurbo,gaieepo/HubTurbo,Honoo/HubTurbo,HyungJon/HubTurbo,Honoo/HubTurbo,HyungJon/HubTurbo,saav/HubTurbo,Sumei1009/HubTurbo,ianngiaw/HubTurbo