Dont skip extension point

- If the contact has no avatar the tooltip extension point was not executed

gajim/gtk/tooltips.py

@@ -449,8 +449,7 @@ class RosterTooltip(StatusTable):
         scale = self._ui.tooltip_grid.get_scale_factor()
         surface = app.contacts.get_avatar(
             account, self.prim_contact.jid, AvatarSize.TOOLTIP, scale)
-        if surface is None:
-            return
+        if surface is not None:
             self._ui.avatar.set_from_surface(surface)
             self._ui.avatar.show()