misc: remove leftover error display code (#23975)

This was only used in signature mode, that got removed in #4744.

wcs/forms/root.py

@@ -1089,14 +1089,6 @@ class FormPage(Directory):
         r += htmltext('</div>')
         return r.getvalue()
 
-    def error(self, msg):
-        self.html_top(self.formdef.name)
-        homepage = get_publisher().get_root_url()
-        r = TemplateIO(html=True)
-        r += htmltext('<div class="errornotice">%s</div>') % msg
-        r += htmltext('<a href="%s">%s</a>') % (homepage, _('Back Home'))
-        return r.getvalue()
-
     def tryauth(self):
         return tryauth(self.formdef.get_url())