[FIX] web: handle empty notebooks in form views

Before this commit, when re-activating a previously active notebook tab, the form
renderer would assume that a tab was actually active. However this does not happen
if no tab is visible or defined and it results in a crash instead.

Now, if no active tab is found, a default active tab (0 = first) is set. This only
helps to prevent the crash and does not affect the current behaviour.

closes odoo/odoo#50006

X-original-commit: 73e0c0a1395ebd0e2b4ac7f857c863a0358c5e17
Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>
Signed-off-by: Julien Mougenot (jum) <jum@odoo.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/addons/web/static/src/js/views/form/form_renderer.js b/addons/web/static/src/js/views/form/form_renderer.js
index 08819f79f57..1b672bdee19 100644
--- a/addons/web/static/src/js/views/form/form_renderer.js
+++ b/addons/web/static/src/js/views/form/form_renderer.js
@@ -213,9 +213,9 @@ var FormRenderer = BasicRenderer.extend({
         for (const notebook of this.el.querySelectorAll(':scope div.o_notebook')) {
             const name = notebook.dataset.name;
             const navs = notebook.querySelectorAll(':scope .o_notebook_headers .nav-item > .nav-link');
-            state[name] = [...navs].findIndex(
+            state[name] = Math.max([...navs].findIndex(
                 nav => nav.classList.contains('active')
-            );
+            ), 0);
         }
         return state;
     },
@@ -247,6 +247,9 @@ var FormRenderer = BasicRenderer.extend({
                 // We can't base the amount on the 'navs' length since some overrides
                 // are adding pageless nav items.
                 const validTabsAmount = pages.length;
+                if (!validTabsAmount) {
+                    continue; // No page defined on the notebook.
+                }
                 let activeIndex = state[name];
                 if (navs[activeIndex].classList.contains('o_invisible_modifier')) {
                     activeIndex = [...navs].findIndex(