Test ab-err-xs0006-005

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"
                xmlns:t="http://xproc.org/ns/testsuite/3.0" version="3.0">
   <p:output port="result">
      <result/>
   </p:output>
   <p:group>
      <p:output port="result"/>
      <p:identity>
         <p:with-input>
            <doc/>
         </p:with-input>
      </p:identity>
      <p:sink/>
   </p:group>
</p:declare-step>