Note that the change in the style of the error part removed the cross icon. It should be added back. Since it's a small change too, it'd make sense to do both of those together.
See https://github.com/xwiki/xwiki-platform/commit/ab67f6b31fe1b0d33d48c6bd8b315f91d7ce5b85#diff-b7941172e2c71037436cfafe8a9ae0468e9f46ca86d57773940cf8a3153d6df2L202-L204
