Checks not required option with default value is type checked.
Test ab-option-018.xml is expected to fail with error code err:XD0036.
<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:p="http://www.w3.org/ns/xproc" xmlns:xs="http://www.w3.org/2001/XMLSchema" version="3.0">
   <p:output port="result">
   <p:option name="option" required="false" select="'default value'" as="xs:boolean">
   <p:identity>
      <p:with-input>
         <doc>{$option}</doc>
      </p:with-input>
   </p:identity>
</p:declare-step>
Add declaration for the xs: namespace
Fix namespace declarations
added new tests