[FIX] web: call do_hide/do_show on a destroyed widget

Before this commit, calling do_hide/do_show/do_toggle on a
widget that had been destroyed before being rendered crashed
(because this.$el was undefined).

Obviously, calling those methods in this situation is useless, but
with asynchronous code, it might happen that you call them in an
handler, and they have been destroyed meanwhile.

This commit checks if this.$el is set before accessing it to avoid
the crash.

closes odoo/odoo#65870

Signed-off-by: Géry Debongnie (ged) <ged@openerp.com>

addons/web/static/src/js/core/widget.js

@@ -181,13 +181,17 @@ var Widget = core.Class.extend(mixins.PropertiesMixin, ServicesMixin, {
      * Hides the widget
      */
     do_hide: function () {
-        this.$el.addClass('o_hidden');
+        if (this.$el) {
+            this.$el.addClass('o_hidden');
+        }
     },
     /**
      * Displays the widget
      */
     do_show: function () {
-        this.$el.removeClass('o_hidden');
+        if (this.$el) {
+            this.$el.removeClass('o_hidden');
+        }
     },
     /**
      * Displays or hides the widget
@@ -196,7 +200,7 @@ var Widget = core.Class.extend(mixins.PropertiesMixin, ServicesMixin, {
     do_toggle: function (display) {
         if (_.isBoolean(display)) {
             display ? this.do_show() : this.do_hide();
-        } else {
+        } else if (this.$el) {
             this.$el.hasClass('o_hidden') ? this.do_show() : this.do_hide();
         }
     },

addons/web/static/tests/core/widget_tests.js

@@ -442,6 +442,27 @@ QUnit.module('core', {}, function () {
         parent.destroy();
     });
 
+    QUnit.test("calling do_hide on a widget destroyed before being rendered", async function (assert) {
+        assert.expect(1);
+
+        const MyWidget = Widget.extend({
+            willStart() {
+                return new Promise(() => {});
+            }
+        });
+
+        const widget = new MyWidget();
+        widget.appendTo(document.createDocumentFragment());
+        widget.destroy();
+
+        // those calls should not crash
+        widget.do_hide();
+        widget.do_show();
+        widget.do_toggle(true);
+
+        assert.ok(true);
+    });
+
     QUnit.test('start is not called when widget is destroyed', function (assert) {
         assert.expect(0);
         var slowWillStartDef = $.Deferred();