[F&O] 16 Context function: Empty context

Definition for fn:context-item, fn:last, fn:position states:
'Returns the empty sequence if the context is the empty sequence'.

It should be rather 'if there is no context item' as in other parts of spec
Context *is* item and could not be empty.
Also there is no precise definition of term 'there is no context item'.

Definition of dynamic context states:
'If evaluation of an expression relies on some part of the dynamic context
that has not been assigned a value, a dynamic error is raised.'
but functions above 'relies' on context item to check if it is not defined
and aren't raising error, so it is not the case.

Regards,
Noe Michejda
7th Portal S.C.