Test nw-err-xs0015-007

The pipeline

<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:ex="http://test" xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
   <p:output port="result"/>
   <p:try>
      <p:identity>
         <p:with-input>
            <doc/>
         </p:with-input>
      </p:identity>
      <p:catch/>
   </p:try>
</p:declare-step>