Failed to Execute JavaScript on iOS 11.3.1 and Safari


When trying to execute Javascript command on real iOS device with Safari 11, using Python code generated by AppiumStudio we get error.I would like to point out that its not only for timing but for some other javascript calls also.
As this is first post it doesnt allow me to post more then 2 links in post.
HW and SW used:
1.Device iOS: iPhone 7
2. Appium Studio v11.7.103
3.Python-Appium-Client version: 0.26
4.Selenium version: 3.12.0

AppiumStudio Code:
import unittest
import time
from appium import webdriver
from import WebDriverWait
from import By
from import expected_conditions

class test1(unittest.TestCase):
reportDirectory = ‘reports’
reportFormat = ‘xml’
dc = {}
testName = ‘test1’
driver = None

def setUp(self):
    self.dc['reportDirectory'] = self.reportDirectory
    self.dc['reportFormat'] = self.reportFormat
    self.dc['testName'] = self.testName
    self.dc['udid'] = '5e08285bf62c12fef5606b28b99b40d889491b7c'
    self.dc['browserName'] = 'Safari'
    self.dc['platformName'] = 'ios'
    self.driver = webdriver.Remote('http://localhost:4723/wd/hub',self.dc)

def testtest1(self):
    result1 = self.driver.execute_script("var a = window.performance.timing")

def tearDown(self):
if __name__ == '__main__':