Fix all type errors in design system (#3956)

* 📘 Fix type errors in design system

* 🔥 Remove unneeded `?`

* 🔧 Add design system to Vetur

* 📘 Improve typing of `$el`

* ♻️ Address feedback

* 📘 Type leftover `MouseEvent`

* 📘 Type `event.target` properly

packages/design-system/src/components/N8nActionToggle/ActionToggle.vue

@@ -35,8 +35,9 @@ import ElDropdown from 'element-ui/lib/dropdown';
 import ElDropdownMenu from 'element-ui/lib/dropdown-menu';
 import ElDropdownItem from 'element-ui/lib/dropdown-item';
 import N8nIcon from '../N8nIcon';
+import Vue from 'vue';
 
-export default {
+export default Vue.extend({
 	name: 'n8n-action-toggle',
 	components: {
 		ElDropdown,
@@ -79,7 +80,7 @@ export default {
 			this.$emit('visible-change', value);
 		},
 	},
-};
+});
 </script>
 
 <style lang="scss" module>