fixing misc nb title by GET param

modules/fontane/misc.xqm

@@ -21,7 +21,9 @@ function f-misc:get-title-by-baseUri($baseUri as xs:string) as xs:string? {
 
 declare function f-misc:nb-param-to-title($node as node(), $model as map(*), $nb)
 as xs:string? {
-    f-misc:get-title-by-baseUri( "textgrid:" || $nb )
+  if($nb = "")
+  then ""
+  else f-misc:get-title-by-baseUri( "textgrid:" || $nb )
 };
 
 declare function f-misc:cite($node as node(), $model as map(*)) {