Join Room : fallback to show Join button when RoomContent is Unknown (preview fails)

features/joinroom/impl/src/main/kotlin/io/element/android/features/joinroom/impl/JoinRoomState.kt

@@ -37,7 +37,11 @@ data class JoinRoomState(
     val eventSink: (JoinRoomEvents) -> Unit
 ) {
     val joinAuthorisationStatus = when (contentState) {
+        // Use the join authorisation status from the loaded content state
         is ContentState.Loaded -> contentState.joinAuthorisationStatus
+        // Assume that if the room is unknown, the user can join it
+        is ContentState.UnknownRoom -> JoinAuthorisationStatus.CanJoin
+        // Otherwise assume that the user can't join the room
         else -> JoinAuthorisationStatus.Unknown
     }
 }