removing running managed server fails without failure-description

server asdfasd is running. Removing it results in

[domain@localhost:9999 host=master] ./server-config=asdfasd:remove
{
"outcome" => "failed",
"result" => undefined,
"rolled-back" => true,
"server-groups" => undefined
}

There should be a failure description telling that the server needs to be :stop'ed first.