Test err:XS0001 002

The pipeline

<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
   <p:identity name="step-a">
      <p:with-input port="source">
         <p:pipe step="step-b" port="result"/>
      </p:with-input>
   </p:identity>
   <p:identity name="step-b">
      <p:with-input port="source">
         <p:pipe step="step-a" port="result"/>
      </p:with-input>
   </p:identity>
</p:declare-step>