Don't add empty auto join channels

Author: Gatsik

src/util/settings_menus.py

@@ -604,8 +604,8 @@ def save_splitter_sizes(self) -> None:
 
     def add_autojoin_channel(self) -> None:
         channel, ok = QInputDialog.getText(self, "Add Channel", "Enter channel name:")
-        if ok:
-            self.listAutojoinChannels.addItem(channel.removeprefix("#").strip())
+        if ok and (normalized_name := channel.removeprefix("#").strip()):
+            self.listAutojoinChannels.addItem(normalized_name)
             self.enable_apply_button()
 
     def remove_autojoin_channel(self) -> None: