[FIX] web: missing required attribute for html field

To reproduce
============

* referrals -> configuration -> rewards
* try creating a new reward keeping description empty
* here description is required html field
* traceback on clicking save

Problem
=======
in case of html field, `this.data[fieldName]` is an object `Markup{''}`,
so `!this.data[fieldName]` is always `false` as objects are considered
as true value in JS.

Solution
========
in case of html, check the length of the Markup object

opw-3469539

closes odoo/odoo#134365

X-original-commit: dce8e1a8b6137c035488240f8004b870b73c8d51
Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>
Signed-off-by: Abdelouahab Laaroussi (abla) <abla@odoo.com>
Co-authored-by: Niyas Raphy <https://github.com/niyasraphy>

addons/web/static/src/model/relational_model/record.js

@@ -335,6 +335,11 @@ export class Record extends DataPoint {
                 case "integer":
                 case "monetary":
                     continue;
+                case "html":
+                    if (this._isRequired(fieldName) && this.data[fieldName].length === 0) {
+                        unsetRequiredFields.push(fieldName);
+                    }
+                    break;
                 case "one2many":
                 case "many2many": {
                     const list = this.data[fieldName];

addons/web/static/tests/views/fields/html_field_tests.js

@@ -57,6 +57,32 @@ QUnit.module("Fields", ({ beforeEach }) => {
         assert.strictEqual(target.querySelector(".o_field_html").textContent, "some text");
     });
 
+    QUnit.test("html field with required attribute", async function (assert) {
+        await makeView({
+            type: "form",
+            resModel: "partner",
+            resId: 1,
+            serverData,
+            arch: /* xml */ `<form><field name="txt" required="1"/></form>`,
+        });
+
+        const textarea = target.querySelector(".o_field_html textarea");
+        assert.ok(textarea, "should have a text area");
+
+        await editInput(textarea, null, "");
+        assert.strictEqual(textarea.value, "");
+
+        await clickSave(target);
+        assert.strictEqual(
+            target.querySelector(".o_notification_title").textContent,
+            "Invalid fields: "
+        );
+        assert.strictEqual(
+            target.querySelector(".o_notification_content").innerHTML,
+            "<ul><li>txt</li></ul>"
+        );
+    });
+
     QUnit.test("html fields are correctly rendered (edit)", async (assert) => {
         await makeView({
             type: "form",