[FIX] web_editor: avoid traceback on form inputs double-clicks

Before this commit, double clicking on the border or on the padding of
a form input generated a traceback.

task-2312878

closes odoo/odoo#61201

X-original-commit: 904af21214a5a6924ec80b5690a523819aaec5f1
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web_editor/static/src/js/editor/snippets.options.js

@@ -279,6 +279,13 @@ const UserValueWidget = Widget.extend({
      * Closes the widget (only meaningful for widgets that can be closed).
      */
     close: function () {
+        if (!this.el) {
+            // In case the method is called while the widget is not fully
+            // initialized yet. No need to prevent that case: asking a non
+            // initialized widget to close itself should just not be a problem
+            // and just be ignored.
+            return;
+        }
         this.trigger_up('user_value_widget_closing');
         this.el.classList.remove('o_we_widget_opened');
         this._userValueWidgets.forEach(widget => widget.close());