Note that json and jsonb extraction operators no longer consider a
negative subscript to be invalid.
+
+ Allow json> and jsonb> extraction operators to
+ accept negative subscripts, which count from the end of JSON
+ arrays. Historically, these operators yielded NULL>
+ in the event of a negative subscript, because negative
+ subscripts were considered invalid. (Peter Geoghegan, Andrew
+ Dunstan)
+
+
+