[FIX] web: views: basic relational model: can save without any dirty translatable fields

Be in another language, edit and save a record which has translatable fields.

Before this commit, there was a crash because no changes were done on the record, making
a programming error.

After this commit, we can edit and save a record with translatable fields without changes.

closes odoo/odoo#97240

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>

addons/web/static/src/views/basic_relational_model.js

@@ -286,9 +286,11 @@ export class Record extends DataPoint {
     }
 
     get dirtyFields() {
-        return Object.keys(this.model.__bm__.localData[this.__bm_handle__]._changes).map(
-            (change) => this.activeFields[change]
-        );
+        const changes = this.model.__bm__.localData[this.__bm_handle__]._changes;
+        if (!changes) {
+            return [];
+        }
+        return Object.keys(changes).map((change) => this.activeFields[change]);
     }
 
     get translatableFields() {

addons/web/static/tests/views/form/form_view_tests.js

@@ -7844,6 +7844,42 @@ QUnit.module("Views", (hooks) => {
         );
     });
 
+    QUnit.test("can save without any dirty translatable fields", async function (assert) {
+        serverData.models.partner.fields.foo.translate = true;
+
+        patchWithCleanup(localization, {
+            multiLang: true,
+        });
+
+        await makeView({
+            type: "form",
+            resModel: "partner",
+            serverData,
+            arch: `
+                <form>
+                    <field name="foo"/>
+                </form>`,
+            resId: 1,
+            mockRPC(route, args) {
+                assert.step(args.method);
+            },
+        });
+
+        assert.verifySteps(["get_views", "read"]);
+        await clickEdit(target);
+        assert.containsOnce(target, ".o_form_editable");
+        // o_field_translate is on the input and on the translate button
+        assert.containsN(target, "div[name='foo'] > .o_field_translate", 2);
+        await clickSave(target);
+        assert.containsNone(
+            target,
+            ".alert .o_field_translate",
+            "should not have a translation alert"
+        );
+        assert.containsOnce(target, ".o_form_readonly");
+        assert.verifySteps([]);
+    });
+
     QUnit.test("translation alerts are preserved on pager change", async function (assert) {
         serverData.models.partner.fields.foo.translate = true;