[BUG] More panics...

[evanlinjin]

panic: invalid rule

goroutine 31 [running]:
github.com/skycoin/skywire/pkg/routing.Rule.TransportID(0x7f36429890a5, 0x36, 0x36, 0x0, 0x0)
        /home/evanlinjin/dev/skycoin/skywire/pkg/routing/rule.go:70 +0x13f
github.com/skycoin/skywire/pkg/router.(*Router).forwardPacket(0xc0001e08c0, 0xec5640, 0xc00002c138, 0xc0005f6ac6, 0xb, 0x1a, 0x7f36429890a5, 0x36, 0x36, 0x3, ...)
        /home/evanlinjin/dev/skycoin/skywire/pkg/router/router.go:219 +0x28f
github.com/skycoin/skywire/pkg/router.(*Router).handlePacket(0xc0001e08c0, 0xec5640, 0xc00002c138, 0xc0005f6ac0, 0x11, 0x20, 0xeb6b40, 0xc00030ff00)
        /home/evanlinjin/dev/skycoin/skywire/pkg/router/router.go:143 +0x4d4
github.com/skycoin/skywire/pkg/router.(*Router).Serve.func1(0xc0001e08c0, 0xec5640, 0xc00002c138)
        /home/evanlinjin/dev/skycoin/skywire/pkg/router/router.go:116 +0x107
created by github.com/skycoin/skywire/pkg/router.(*Router).Serve
        /home/evanlinjin/dev/skycoin/skywire/pkg/router/router.go:110 +0x109