Correct "Empty room" display

src/python/matrix_client.py

@@ -713,7 +713,7 @@ class MatrixClient(nio.AsyncClient):
 
         self.models[Room, self.user_id][room.room_id] = Room(
             room_id        = room.room_id,
-            display_name   = room.display_name,
+            display_name   = room.display_name or "",
             avatar_url     = room.gen_avatar_url or "",
             topic          = HTML_FILTER.filter_inline(room.topic or ""),
             inviter_id     = inviter,

src/qml/Chat/RoomHeader.qml

@@ -30,7 +30,7 @@ Rectangle {
 
         HLabel {
             id: roomName
-            text: chatPage.roomInfo.display_name
+            text: chatPage.roomInfo.display_name || qsTr("Empty room")
             font.pixelSize: theme.fontSize.big
             color: theme.chat.roomHeader.name
             elide: Text.ElideRight

src/qml/SidePane/RoomDelegate.qml

@@ -37,8 +37,7 @@ HTileDelegate {
     }
 
     title.color: theme.sidePane.room.name
-    title.text: model.data.display_name || "<i>Empty room</i>"
-    title.textFormat: model.data.display_name? Text.PlainText : Text.StyledText
+    title.text: model.data.display_name || qsTr("Empty room")
 
     additionalInfo.children: HIcon {
         svgName: "invite-received"