Quick and dirty way to switch vscode theme between light and dark. Put it into crontab for auto switch day/night.

switch_vscode_theme.py

#!/usr/bin/env python
import json

path = '/Users/your_user/Library/Application Support/Code/User/settings.json'
theme_day = 'Default Light+'
theme_night = 'Default Dark+'

with open(path, 'r') as settings_file:
    data = json.load(settings_file)
    data['workbench.colorTheme'] =  theme_day if data['workbench.colorTheme'] == theme_night else theme_night

with open(path, 'w') as settings_file:
    json.dump(data, settings_file,indent=4)

Put it into crontab like so:

#Mins   Hours  Days  Months   Day of the week                                                                                                                     
0       20     *     *        *              /your/path/switch_vscode_theme.py
0       9      *     *        *              /your/path/switch_vscode_theme.py

You can open the settings like so:

env EDITOR=vim crontab -e

If you don't mind, have a look at my extension ThemeSwitch for a less dirty way of doing this.