Before this commit, having a `customize_show` on an ir.ui.view record in a theme module would be ignored when creating the theme.ir.ui.view as the field would not exists. Actually it would log a warning on create (module install) and raise a traceback on module update (theme update). closes odoo/odoo#39216 Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>