Fix masonry configuration failure (#1970)

Fixes #1964.

Signed-off-by: Florian Hotze <florianh_dev@icloud.com>

bundles/org.openhab.ui/web/src/pages/settings/pages/layout/layout-edit.vue

@@ -311,6 +311,7 @@ export default {
       if (!component.slots.masonry || !component.slots.masonry.length) {
         this.$set(this.page.slots, 'masonry', [{
           component: 'oh-masonry',
+          config: {},
           slots: { default: [] }
         }])
       }