error featured products with smarty cache

[mpiu]

with the smarty cache activated, the products on display in the home disappear. (prestashop 1.7.5 con php 7.1) debugging reports the following error:

 

(1/1) ContextErrorException

Notice: Undefined index: products

in 21eafe86626b9746f9d9d8d63922d2976476d568.psfeaturedproductsviewste.php line 53

at content_5f16c0b45da8e2_07340736(object(SmartyCustomTemplate))in smarty_template_resource_base.php line 123

at Smarty_Template_Resource_Base->getRenderedTemplateCode(object(SmartyCustomTemplate))in smarty_template_cached.php line 137

at Smarty_Template_Cached->render(object(SmartyCustomTemplate), false)in smarty_internal_template.php line 211

at Smarty_Internal_Template->render(false, 0)in smarty_internal_templatebase.php line 232

at Smarty_Internal_TemplateBase->_execute(object(SmartyCustomTemplate), null, null, null, 0)in smarty_internal_templatebase.php line 116

at Smarty_Internal_TemplateBase->fetch(null, null, null, null, false, true, false)in SmartyCustomTemplate.php line 34

at SmartyCustomTemplateCore->fetch()in Module.php line 2413

at ModuleCore->fetch('module:ps_featuredproducts/views/templates/hook/ps_featuredproducts.tpl', 'ps_featuredproducts|1|1|1|1|1|21')in ps_featuredproducts.php line 252

at Ps_FeaturedProducts->renderWidget('displayHome', array('cookie' => object(Cookie), 'cart' => object(Cart)))in Hook.php line 971

at HookCore::coreRenderWidget(object(Ps_FeaturedProducts), 'displayHome', array('cookie' => object(Cookie), 'cart' => object(Cart)))in Hook.php line 923

at HookCore::exec('displayHome')in IndexController.php line 39

at IndexControllerCore->initContent()in Controller.php line 281

at ControllerCore->run()in Dispatcher.php line 509

at DispatcherCore->dispatch()in index.php line 28