If VALUES result set is empty, an exception is thrown

[graue70]

The following query yields an expected result:

PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
SELECT ?entity WHERE {
     values ?search { "inventor"@en } .
     ?entity @en@skos:altLabel ?search
}

However, the following query (remove the 'r' in 'inventor')

PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
SELECT ?entity WHERE {
     values ?search { "invento"@en } .
     ?entity @en@skos:altLabel ?search
}

yields the following error:

Unknown error
Exception: BAD INPUT STRING (The word "invento"@enis not part of the vocabulary.; in /app/src/engine/Values.cpp, line 147, function static void Values::writeValues(IdTable*, const Index&, const SparqlValues&) [with long unsigned int I = 1; IdTable = IdTableStatic<>])

I was expecting an empty result set and find it strange to see an error instead.

[niklas88]

@graue70 agree that doesn't look like the expected behaviour to me either (even without looking at the spec). @floriankramer?

[graue70]

To further make my point: The following query yields the expected empty result set with no error:

PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
SELECT ?entity WHERE {
     ?entity @en@skos:altLabel "invento"@en
}