message: side drawer: disable url open button if no url
diff: @@ -25,6 +25,7 @@ export default function Url(props: TextFieldProps) {
  target="_blank"
  rel="noopener noreferer"
  style={{ width: 56 }}
  + disabled={!props.field.value}
  >
  <LaunchIcon />
  </IconButton>
  