handling pg_typeof undefined

lib/cartodb/models/dataview/base.js

@@ -52,6 +52,11 @@ module.exports = class BaseDataview {
             if (err) {
                 return callback(err);
             }
+
+            if (!result || !result.rows || !result.rows.length) {
+                return callback(new Error('The column type could not be determined'));
+            }
+
             const pgType = result.rows[0].pg_typeof;
             callback(null, getPGTypeName(pgType));
         }, readOnlyTransaction);