[AutoAdd] Fixed error dialog not being shown on error

This happened due to the removal of `exception_msg` attribute, which was
removed with the changes to `RPC` protocol in commit 9b812a4.
Now we access the message using the `message` attribute.

Closes: deluge-torrent/deluge#332
Closes: https://dev.deluge-torrent.org/ticket/3069

deluge/plugins/AutoAdd/deluge_autoadd/gtkui.py

@@ -324,7 +324,7 @@ class OptionsDialog:
             dialogs.ErrorDialog(_('Incompatible Option'), str(ex), self.dialog).run()
 
     def on_error_show(self, result):
-        d = dialogs.ErrorDialog(_('Error'), result.value.exception_msg, self.dialog)
+        d = dialogs.ErrorDialog(_('Error'), result.value.message, self.dialog)
         result.cleanFailure()
         d.run()
 

deluge/ui/console/cmdline/commands/connect.py

@@ -58,13 +58,8 @@ class Command(BaseCommand):
                 return component.start()
 
             def on_connect_fail(result):
-                try:
-                    msg = result.value.exception_msg
-                except AttributeError:
-                    msg = result.value.message
                 self.console.write(
-                    '{!error!}Failed to connect to %s:%s with reason: %s'
-                    % (host, port, msg)
+                    f'{{!error!}}Failed to connect to {host}:{port} with reason: {result.value.message}'
                 )
                 return result