Edit User page fails to load after a user registration

I am logged in as my admin user after a clean startup and can view the edit user page. Then a user registers (they do not need to complete the registration by following the link sent by email). Now the edit user page fails to display, with this error message:

Error executing tag <s2ui:textFieldRow>: No such property: authority for class: java.lang.String

I have traced this to the first call to s2ui:textFieldRow for the username, and further to the fieldErrors() method:

def fieldErrors = { attrs ->
def bean = attrs.remove('bean')
if (bean) {
out << eachError(attrs, {
out << "<span class='s2ui_error'>$

</span>"
})
}
}

If I change the .remove() to a .get() I no longer experience this problem. However, I have no clue how this relates to the user registration.