In Chrome:

File "...\Python36\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 635, in execute_script 'args': converted_args})['value']
File "...\Python36\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 320, in execute
self.error_handler.check_response(response)
File "...\Python36\lib\site-packages\selenium\webdriver\remote\errorhandler.py", line 242, in check_response
raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: unknown error: Cannot read pro'scrollIntoView' of null
In Firefox:
raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.JavascriptException: Message: TypeError: arguments[0] is null
Browser info: chrome=68.0.3440.106
Driver info: chromedriver=2.41.578737
Platform=Windows NT 6.1.7601 SP1 x86_64
                The exception message tells you what the issue is... arguments[0] is null. Whatever you are passing in as final_side is null. Take some time to debug your code and trace back how final_side gets to be null. We can't do that for you because you've only included a single line of code. Also, please fix the formatting of your error messages. The mix of regular text, code, and bold is hard to read and follow.
– JeffC
                Aug 30, 2018 at 13:17
This error message...
selenium.common.exceptions.JavascriptException: Message: TypeError: arguments[0] is null
...implies that the WebElement referred as arguments[0] is null i.e. doesn't contain any reference.
Your main issue is the WebElement you are referring as final_side doesn't contain any reference to any element within the webpage.
Without the previous commands and relevant HTML it is tough to guess the exact reason of the error.
Solution
A possible solution would be to induce WebDriverWait for the desired element to be visible within the HTML DOM as follows:
element = WebDriverWait(self.driver, 10).until(EC.visibility_of_element_located((By.CSS_SELECTOR, "element_css")))
self.driver.execute_script("return arguments[0].scrollIntoView(true);", element)
        
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