Embedded triple expression label not getting recognized

[hsolbrig]

The following:

BASE <https://w3id.org/biolink/vocab/>

<BiologicalProcess> ( 
    {
        ( $<BiologicalProcess_tes> a [ <BiologicalProcessOrActivity> ] ?;
          a [ <BiologicalProcess> ]
        )
    } OR @<X>
)

<X> {&<BiologicalProcess_tes>}

Fails to record the triple expression label <BiologicalProcess_tes>.

1) This is not detected until runtime -- the missing label goes unrecognized unless one attempts to evaluate <X> 2) There is a error in the message when it is detected: Testing :s against shape https://w3id.org/biolink/vocab/X\n {expr}: Reference not found