Fix hstore bug when parsing null values (#1504)

lib/dialects/postgres/hstore.js

@@ -43,6 +43,8 @@ module.exports = {
     
     
     const rx = /\"((?:\\\"|[^"])*)\"\s*\=\>\s*((?:true|false|NULL|\d+|\d+\.\d+|\"((?:\\\"|[^"])*)\"))/g
     const rx = /\"((?:\\\"|[^"])*)\"\s*\=\>\s*((?:true|false|NULL|\d+|\d+\.\d+|\"((?:\\\"|[^"])*)\"))/g
 
 
+    string = string || '';
+
     string.replace(rx, function(match, key, value, innerValue) {
     string.replace(rx, function(match, key, value, innerValue) {
       switch(value) {
       switch(value) {
         case 'true':
         case 'true':

test/postgres/hstore.test.js

@@ -90,6 +90,11 @@ if (dialect.match(/^postgres/)) {
     })
     })
 
 
     describe('parse', function() {
     describe('parse', function() {
+      it('should handle null objects correctly', function(done) {
+        expect(hstore.parse(null)).to.deep.equal({ })
+        done()
+      })
+
       it('should handle empty objects correctly', function(done) {
       it('should handle empty objects correctly', function(done) {
         expect(hstore.parse('')).to.deep.equal({ })
         expect(hstore.parse('')).to.deep.equal({ })
         done()
         done()