Offline: XPath error in demo form with "Copy data (with warning)"

[ebruchez]

• load /fr/orbeon/builder/edit/4da83f8626b0e8f3f29ae554780c060312e04d02
• Test Offline
• change "value 2-3" to something else
• getting error

An empty sequence is not allowed as the value in 'cast as' expression

The only place we use this is in buttons-bar.xsl:

<xf:var name="highlight-primary-opt"   as="xs:boolean?" value="fr:component-param-value('highlight-primary')  [. = ('true', 'false')] cast as xs:boolean?"/>
<xf:var name="inverse-opt"             as="xs:boolean?" value="fr:component-param-value('inverse')            [. = ('true', 'false')] cast as xs:boolean?"/>

Although it could also be in dropdown-date.xbl.

if ($r castable as xs:integer) then
    xs:integer($r) cast as xs:integer
...

However, if I change all of these, I still get the error!

In any case, this error seems incorrect, and this works on the JVM. Probably a bug in https://github.com/orbeon/saxon-xpath.

[ebruchez]

Possible next steps:

• try cast as expressions in saxon-xpath tests
• add debug to figure out which expression fails