Test case K-ResolveQNameConstructFunc-4 contains the following:

empty(resolve-QName((), "a string"))

While XPTY0004 is the expected error, the empty sequence should also be accepted.

In section 3.1.5, Function Calls, of XQuery, we say that:

"Argument expressions are evaluated, producing argument values. The order of argument evaluation is implementation-dependent and a function need not evaluate an argument if the function can evaluate its body without evaluating that argument."

In section 11.1.1, fn:resolve-QName, F&O says, "If $qname is the empty sequence, returns the empty sequence."