Merge: - dhcp: crash on error on startup

Squashed commit of the following:

commit 81908b636ec91a562b3ff8634b77c71dc3f009e4
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Mar 13 17:25:36 2020 +0300

    - dhcp: crash on error on startup

home/home.go

@@ -192,6 +192,9 @@ func run(args options) {
 	config.DHCP.HTTPRegister = httpRegister
 	config.DHCP.ConfigModified = onConfigModified
 	Context.dhcpServer = dhcpd.Create(config.DHCP)
+	if Context.dhcpServer == nil {
+		os.Exit(1)
+	}
 	Context.clients.Init(config.Clients, Context.dhcpServer)
 	config.Clients = nil