Try/catch 005

The pipeline

<p:declare-step xmlns:cx="http://xmlcalabash.com/ns/extensions" xmlns:p="http://www.w3.org/ns/xproc" name="main" version="3.0">
                <!-- we should replace cx with something better -->
   <p:option name="error"/>
   <p:output port="result">
      <p:pipe step="try" port="finally"/>
   </p:output>
   <p:try name="try">
      <p:group>
         <p:choose>
            <p:when test="$error = 0">
               <p:identity>
                  <p:with-input port="source">
                     <p:inline>
                        <doc>try succeeded</doc>
                     </p:inline>
                  </p:with-input>
               </p:identity>
            </p:when>
            <p:when test="$error = 1">
               <p:error code="cx:error">
                  <p:with-input port="source">
                     <p:empty/>
                  </p:with-input>
               </p:error>
            </p:when>
            <p:otherwise>
               <p:error code="cx:error2">
                  <p:with-input port="source">
                     <p:empty/>
                  </p:with-input>
               </p:error>
            </p:otherwise>
         </p:choose>
      </p:group>
      <p:catch code="cx:error">
         <p:identity>
            <p:with-input port="source">
               <p:inline>
                  <doc>caught cx:error</doc>
               </p:inline>
            </p:with-input>
         </p:identity>
      </p:catch>
      <p:catch>
         <p:identity>
            <p:with-input port="source">
               <p:inline>
                  <doc>caught any</doc>
               </p:inline>
            </p:with-input>
         </p:identity>
      </p:catch>
      <p:finally>
         <p:output port="finally" primary="false">
            <p:pipe step="fident" port="result"/>
         </p:output>
         <p:identity name="fident">
            <p:with-input port="source">
               <p:inline>
                  <doc>finally</doc>
               </p:inline>
            </p:with-input>
         </p:identity>
      </p:finally>
   </p:try>
</p:declare-step>