After a quick google - found a solution on reddit:
this is the list of recommendations that I've compiled for players facing the problem:
- Make sure your device's disk space and memory aren't full or close to their limits (this should be an uncommon issue, but still a potential problem).
- Load your latest save (if you've come accross the localStorage quota error, it's possible that some variables have got corrupted).
- Save the game as a savefile using the "Save to Disk..." option in the Saves Menu.
- Turn off [any kind of] auto-save feature.
- Delete your saves stored in memory in the Saves Menu.
- Clear your browser's cache and cookies (by far the most helpful).
(Edit:) * According to player reports, trying to play the game on a different browser may also fix this issue.
I suspect you'll have to clear your cache and cookies. Heads up - that WILL delete all the IF saves you've made on your browser.
PS.: It's good practice to look up the issue you're having. There's probably somebody on reddit that had the same issue and solved it.