Error with weblink component

I get an error with weblink component:

panic: interface conversion: interface is nil, not string

goroutine 1 [running]:
panic(0x2f8720, 0x44200488c0)
/home/travis/.gimme/versions/go1.7.6.linux.amd64/src/runtime/panic.go:500 +0x390, 0x24, 0x200, 0x0)
/home/travis/gopath/src/ +0x404, 0xd, 0x7ffb02ce5c, 0x7, 0x0, 0x0, 0x49a900, 0x0, 0x0, 0x0, …)
/home/travis/gopath/src/ +0x31c
/home/travis/gopath/src/ +0x540, 0x372ff0, 0x44200829a0, 0x0, 0x0)
/home/travis/gopath/src/ +0x118, 0xd, 0x0, 0x0, 0x49a280, 0x1, 0x1, 0x350d84, 0x2f, 0x0, …)
/home/travis/gopath/src/ +0x7b0*App).Run(0x44200e2000, 0x442000a150, 0x3, 0x3, 0x0, 0x0)
/home/travis/gopath/src/ +0x950
/home/travis/gopath/src/ +0x150`

My configuration.yaml file:
weblink: entities: - name: Router url: icon: mdi:router-wireless

My hassio version:
hassio ha info
{ "result": "ok", "data": { "version": "0.77.3", "last_version": "0.77.3", "machine": "raspberrypi3-64", "image": "homeassistant/raspberrypi3-64-homeassistant", "custom": false, "boot": true, "port": 8123, "ssl": false, "watchdog": true, "wait_boot": 600 } }

Many thanks for your help.
Best regards.