Sudden build failure with //types/tslib.d.ts errors

[SunsetRunner]

When I walked away from the PC this morning, my app was building and running just fine. This afternoon, it won't build at all, and the Build Output panel shows maybe 60 errors in //types/tslib.d.ts, on nearly every line number 1 thru 38 of that file, and then more. When I click the error line number at the right side of the Build Output panel, it says "Cannot jump to position; file not found". That's NOT a file I have ever seen or edited, is not referenced anywhere in my code (I text-searched every file in the download), and I cannot find anything in the forums or SDK about it.

I've tried only building (not running), reopened the project, logged out and back in, restarted my browser completely, reverted to an older known working version... nada, zip, nothing. Still cannot build.

Perhaps something broke in the web-based compiler?

[SunsetRunner · Accepted solution]

On further troubleshooting, I found that by loading up in a different browser, it compiled properly. So I then cleared all my Fitbit website cookies and the original browser's cache, and tried again. Success.

I had NOT been able to fix the problem by "force reloading" (with the shift key).

I suspect that the browser was caching an incomplete library file.

So lesson learned: if you have an unexplained error in a library file, try clearing your cache and cookies, and trying again.