Example: id is an INTEGER, tco is a DECIMAL, the table is empty:

scala> DB.runQuery("SELECT SUM(id) FROM contracts")
res9: (List[String], List[List[String]]) = (List(sum),List(List(0)))

scala> DB.runQuery("SELECT SUM(tco) FROM contracts")
java.lang.NullPointerException
at net.liftweb.mapper.DB$.net$liftweb$mapper$DB$$asString(DB.scala:265)
at net.liftweb.mapper.DB$$anonfun$resultSetTo$1.apply(DB.scala:287)
at net.liftweb.mapper.DB$$anonfun$resultSetTo$1.apply(DB.scala:287)
at scala.List.map(List.scala:812)
at net.liftweb.mapper.DB$.resultSetTo(DB.scala:287)
at net.liftweb.mapper.DB$$anonfun$runQuery$2$$anonfun$ap...