segfault on osx

tested on OSX Mojave (10.14) with latest from master.

rage:bitmask-vpn admin$ ./bitmask-vpn
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x4310577]

goroutine 8 [running]:
0xacab.org/leap/bitmask-vpn/vendor/github.com/getlantern/systray.(*MenuItem).SetTitle(0x0, 0xc4201647d0, 0x5)
        /Users/admin/go/src/0xacab.org/leap/bitmask-vpn/vendor/github.com/getlantern/systray/systray.go:110 +0x27
0xacab.org/leap/bitmask-vpn/pkg/systray.(*bmTray).changeStatus(0xc420098700, 0x43e4c65, 0x6)
        /Users/admin/go/src/0xacab.org/leap/bitmask-vpn/pkg/systray/systray.go:235 +0x753
0xacab.org/leap/bitmask-vpn/pkg/systray.(*bmTray).loop(0xc420098700, 0x44328e0, 0xc42015e330, 0xc420160008, 0x442e600, 0xc420162960)
        /Users/admin/go/src/0xacab.org/leap/bitmask-vpn/pkg/systray/systray.go:100 +0xa1d
0xacab.org/leap/bitmask-vpn/pkg/systray.initialize(0xc42008c320, 0xc420098700)
        /Users/admin/go/src/0xacab.org/leap/bitmask-vpn/pkg/systray/run.go:59 +0x2a3
created by 0xacab.org/leap/bitmask-vpn/pkg/systray.Run
        /Users/admin/go/src/0xacab.org/leap/bitmask-vpn/pkg/systray/run.go:28 +0xce