[FIX] web: calendar widget has undefined attrs

Backport of #59876

closes odoo/odoo#60124

X-original-commit: 5d4ae907934b90dda4ac9fb3b5080e632b677219
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>
Signed-off-by: backspac <backspac@users.noreply.github.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/addons/web/static/src/js/views/calendar/calendar_popover.js b/addons/web/static/src/js/views/calendar/calendar_popover.js
index 8e1f5be446b..c3b18676bde 100644
--- a/addons/web/static/src/js/views/calendar/calendar_popover.js
+++ b/addons/web/static/src/js/views/calendar/calendar_popover.js
@@ -165,7 +165,7 @@ var CalendarPopover = Widget.extend(WidgetAdapterMixin, StandaloneFieldManagerMi
                     FieldClass = fieldRegistry.getAny([field.widget, field.type]);
                     fieldWidget = new FieldClass(self, field.name, record, self.displayFields[field.name]);
                 }
-                if (!_.isObject(fieldWidget.attrs.modifiers)) {
+                if (fieldWidget.attrs && !_.isObject(fieldWidget.attrs.modifiers)) {
                     fieldWidget.attrs.modifiers = fieldWidget.attrs.modifiers ? JSON.parse(fieldWidget.attrs.modifiers) : {};
                 }
                 self._registerWidget(recordID, field.name, fieldWidget);