[FIX] web_editor: better error message when missing filename field

closes #112101

Signed-off-by: Rémy Voet <ryv@odoo.com>

addons/web_editor/controllers/main.py

@@ -193,7 +193,7 @@ class Web_Editor(http.Controller):
     @http.route('/web_editor/stars', type='json', auth='user')
     def update_stars(self, res_model, res_id, filename, starsId, rating):
         record = request.env[res_model].browse(res_id)
-        value = getattr(record, filename, False)
+        value = filename in record._fields and record[filename]
         htmlelem = etree.fromstring("<div>%s</div>" % value, etree.HTMLParser())
 
         stars_widget = htmlelem.find(".//span[@id='checkId-%s']" % starsId)