[FIX] web_editor, website(_theme_install): avoid theme.ir.ui.view crash

In a particular case, `_views_get` was mixing apples and oranges, ir.ui.view
and theme.ir.ui.view.

This was the case if a theme has a theme.ir.ui.view t-calling another
theme.ir.ui.view.
(Only theme's sale bridge cause this issue, eg theme_kea_sale.products)
Then, having that theme installed on a website would make all other website
without that theme to crash when opening the /shop customize menu.

Indeed, the theme.ir.ui.view would have the xml_id theme_kea_sale.search.
The generic view `website_sale.products` would have `theme_kea_sale.products`
as inherit child which is website specific and t-call `theme_kea_sale.search`.

Then, on a website witout theme_kea installed, opening the customize menu would
call `get_related_views` that would call `_views_get` that would loop through
inherit children calling `_view_obj` that would not find a view with that key
and would fallback on self.env.ref, finding the theme.ir.ui.view.

Note: `_views_get` might return specific view for another website but that will
      be filtered on `get_related_views` override in website.

Step to reproduce:
  - Have at least 2 websites and website_sale installed
  - Install theme_kea on a website, it will also install theme_kea_sale
  - Go on the website that has not theme_kea installed
  - Go to /shop
  - Open Customize menu, it won't load because of python crash

opw-1914576
Closes #29347

1 files changed, 4 insertions, 3 deletions

diff --git a/addons/web_editor/models/ir_ui_view.py b/addons/web_editor/models/ir_ui_view.py
index 45211502f11..908f58e6b8c 100644
--- a/addons/web_editor/models/ir_ui_view.py
+++ b/addons/web_editor/models/ir_ui_view.py
@@ -205,7 +205,8 @@ class IrUiView(models.Model):
             return self.search([('key', '=', view_id)], limit=1) or self.env.ref(view_id)
         elif isinstance(view_id, pycompat.integer_types):
             return self.browse(view_id)
-        # assume it's already a view object (WTF?)
+        # It can already be a view object when called by '_views_get()' that is calling '_view_obj'
+        # for it's inherit_children_ids, passing them directly as object record.
         return view_id
 
     # Returns all views (called and inherited) related to a view
@@ -224,7 +225,7 @@ class IrUiView(models.Model):
             view = self._view_obj(view_id)
         except ValueError:
             _logger.warning("Could not find view object with view_id '%s'", view_id)
-            return []
+            return self.env['ir.ui.view']
 
         while root and view.inherit_id:
             view = view.inherit_id
@@ -240,7 +241,7 @@ class IrUiView(models.Model):
                 called_view = self._view_obj(child.get('t-call', child.get('t-call-assets')))
             except ValueError:
                 continue
-            if called_view not in views_to_return:
+            if called_view and called_view not in views_to_return:
                 views_to_return += self._views_get(called_view, options=options, bundles=bundles)
 
         extensions = view.inherit_children_ids