sqlite: fix undefined value bug

lib/dialects/sqlite/query-generator.js

@@ -4,7 +4,7 @@ var Utils = require("../../utils")
 var escape = function(str) {
 var escape = function(str) {
   if (typeof str === 'string') {
   if (typeof str === 'string') {
     return "'" + str.replace(/'/g, "''") + "'"
     return "'" + str.replace(/'/g, "''") + "'"
-  } else if(str === null) {
+  } else if(str === null || str === undefined) {
     return 'NULL'
     return 'NULL'
   } else {
   } else {
     return str
     return str