added default authority when a channel has no topic (this shouldn't happen, but does)
added default authority when a channel has no topic (this shouldn't happen, but does)

daukantas/factlink-core,daukantas/factlink-core,Factlink/factlink-core,daukantas/factlink-core,daukantas/factlink-core,Factlink/factlink-core,Factlink/factlink-core,Factlink/factlink-core