avoid exception when region's FileName is null
avoid exception when region's FileName is null

svermeulen/omnisharp-server,OmniSharp/omnisharp-server,syl20bnr/omnisharp-server,mispencer/OmniSharpServer,corngood/omnisharp-server,x335/omnisharp-server,syl20bnr/omnisharp-server,corngood/omnisharp-server,x335/omnisharp-server