Confusion about fn-function-lookup-761 in relation to fn-function-lookup-759

[nkutsche]

Hi, I'm a bit confused about the combination of the test cases fn-function-lookup-759 and fn-function-lookup-761.

The fn-function-lookup-759 says that in any case you should be able to lookup for the function load-xquery-module:

  <test-case name="fn-function-lookup-759" 
             covers="fn-load-xquery-module">
    <description>Attempts to look up function fn:load-xquery-module#1.</description>
    <created by="Tim Mills" on="2016-08-19"/>
    <dependency type="spec" value="XP31+ XQ31+"/>
    <test>exists(function-lookup(fn:QName('http://www.w3.org/2005/xpath-functions', 'load-xquery-module'), 1))</test>
    <result>
      <assert-true/>
    </result>
  </test-case>

Reminder:
The function signature of load-xquery-module#1 is fn:load-xquery-module($module-uri as xs:string) as map(*).

The test case fn-function-lookup-761 says now if you do not support the feature fn-load-xquery-module and make the same lookup as in fn-function-lookup-759 but now call the function with a wrong typed argument, this function must throw an error code FOQM0006:

  <test-case name="fn-function-lookup-761" 
             covers="fn-load-xquery-module"
             covers-30="dynamic-function-call">
    <description>Attempts to invoke function fn:load-xquery-module#1.</description>
    <created by="Tim Mills" on="2016-08-19"/>
    <dependency type="spec" value="XP31+ XQ31+"/>
    <dependency type="feature" value="fn-load-xquery-module" satisfied="false"/>  
    <test>function-lookup(fn:QName('http://www.w3.org/2005/xpath-functions', 'load-xquery-module'), 1)( 0 )</test>
    <result>
      <error code="FOQM0006" />
    </result>
  </test-case>

On my point of view, the error code XPTY0004 for the failed type conversion should be also acceptable, shouldn't it? Otherwise the function returned by function-lookup(fn:QName('http://www.w3.org/2005/xpath-functions', 'load-xquery-module'), 1) must have a signiture which is more lax as the specification requires.