Have one window opened, with the following tabs; Items, variables, scripts, chapters and pages.
Then have another, different window for every game page you want to edit.
After every edit/ addition, copy what you just created and save.
Refresh the tab twice after making any change in the first window's tabs.
After you finish a page, add every link like this: write link name, create the page on which it should land, then close the landing page's window, then next link etc. When you're done, save, then go to the next page you want to edit and save& close the page you finished.
This way, you'll be 99% sure that errors won't occur again.