[FIX] website_blog: Prevent tags loading if no blogs

Steps to reproduce the bug:
- Go to website app > configuration
- Set the visibility of all the blog to Website A (So that it's not visible on Website B)
- Go to the Blog menu of Website B
- A traceback is triggered

Problem:
The `all_tags` function calls an SQL query to get the tags related to the website blog
with a where condition based on the blog_id. But since there is no blog linked to the site.
The request fails and an error is raised.

Solution:
Do not load the tags, if there is no blog for the website.

Opw-2545315

closes odoo/odoo#72636

X-original-commit: 4d8fc86e4e6beb2171e3bebbabd532086d884d59
Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>
Signed-off-by: Djamel Touati <DjamelTouati@users.noreply.github.com>

addons/website_blog/controllers/main.py

@@ -116,7 +116,10 @@ class WebsiteBlog(http.Controller):
             step=self._blog_post_per_page,
         )
 
-        all_tags = blogs.all_tags(join=True) if not blog else blogs.all_tags().get(blog.id, request.env['blog.tag'])
+        if not blogs:
+            all_tags = request.env['blog.tag']
+        else:
+            all_tags = blogs.all_tags(join=True) if not blog else blogs.all_tags().get(blog.id, request.env['blog.tag'])
         tag_category = sorted(all_tags.mapped('category_id'), key=lambda category: category.name.upper())
         other_tags = sorted(all_tags.filtered(lambda x: not x.category_id), key=lambda tag: tag.name.upper())