PurpleConnectionClass.disconnect to chain up or to dispatch

So I wanted to fix that SIGSEGV that’s happening when closing Pidgin3 or when disconnecting an account. The SIGSEGV happens for example when disconnecting an IRCv3 account at parent_class->disconnect in the following code:

static gboolean
purple_ircv3_connection_disconnect(PurpleConnection *purple_connection,
                                   GError **error)
	PurpleIRCv3Connection *connection = NULL;
	PurpleIRCv3ConnectionPrivate *priv = NULL;
	PurpleConnectionClass *parent_class = NULL;

	g_return_val_if_fail(PURPLE_IRCV3_IS_CONNECTION(purple_connection), FALSE);

	/* Chain up to our parent's disconnect to do initial clean up. */
	parent_class = PURPLE_CONNECTION_CLASS(purple_ircv3_connection_parent_class);
	parent_class->disconnect(purple_connection, error);

	connection = PURPLE_IRCV3_CONNECTION(purple_connection);
	priv = purple_ircv3_connection_get_instance_private(connection);

	/* TODO: send QUIT command. */


	return TRUE;

This is because the disconnect function pointer is zero. So the solution seems easy in just checking it for zero before calling it. But I’m wondering why that code is even there in the first place. Because similar code is in Bonjour and XMPP too. Please correct me if I’m wrong but my understanding is that parent_class is PurpleConnection and in purple_connection_disconnect there’s this code:

/* Dispatch to the connection's disconnect method. */
	klass = PURPLE_CONNECTION_GET_CLASS(connection);
	if(klass != NULL && klass->disconnect != NULL) {
		ret = klass->disconnect(connection, error);

Which is the code that calls purple_ircv3_connection_disconnect in the first place and I don’t understand why purple_ircv3_connection_disconnect would need to call its parent’s disconnect again.

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Didn’t I fix this already? It looks like I didn’t but I know I debugged this. Sorry about that…

The old idea was that disconnect would try to set the connection state properties and stuff, but that idea got thrown out the window as the protocols have a much better understanding of that and they should be the one setting it.

So basically there shouldn’t be any chaining up.