So, something broke the browser version with the last update. I've cleared my history, cookies, cache, and restarted my browser, but when I hit menu, I still get a "save corrupted" error for all three files, even though I only ever used one.
There's also no way for me to start a new game. I can still access the import menu where I could paste the information in if I had it, so while it would be inconvenient, I could live with having to copy that information into a text file for later.
There's everything that showed up in the window. The instance of "xr-spatial-tracking" that appears at the bottom of the first picture and the top of the second is the same instance. And there weren't any actual errors, just those warnings.