view bootstrap

hi everybody I installed view bootstrap! I get this error : Notice: Undefined index: classes in template_preprocess_views_bootstrap_media_object() (line 160 of modules/contrib/views_bootstrap/views_bootstrap.theme.inc). template_preprocess_views_bootstrap_media_object(Array, ‘views_bootstrap_media_object’, Array) (Line: 287) DrupalCoreThemeThemeManager->render(Array, Array) (Line: 437) DrupalCoreRenderRenderer->doRender(Array) (Line: 450) DrupalCoreRenderRenderer->doRender(Array, ) (Line: 195) DrupalCoreRenderRenderer->render(Array) (Line: 490) DrupalCoreTemplateTwigExtension->escapeFilter(Object, Array, ‘html’, NULL, 1)[…]