Improve error in case of identifier under Values

Currently executing query insert into "weather" values("a6758b03-854c-40b7-a5c9-a294345b266c", 10.0, 20.0, 15)

we get error sbroad: invalid query: Reference must point to some relational node.

Proposal is too improve handling of such a case:

• Put reference name into the error message
• Check that we deal with single-qouted strings under values and not identifiers. Possibly warn user about it