Unreachable inside unwinding

There is an app that successfully worked with emscripten v1.38.30. After updating emscripten to actual version (2.0.25) and fixing compilation errors, runtime errors, this exception occurs:
RuntimeError: abort(RuntimeError: unreachable) at Error
at jsStackTrace (http://localhost:6931/index.js:2697:14)
at stackTrace (http://localhost:6931/index.js:2712:11)
at abort (http://localhost:6931/index.js:1514:43)
at runAndAbortIfError (http://localhost:6931/index.js:16700:3)
at Object.maybeStopUnwind (http://localhost:6931/index.js:16781:4)
at ret. (http://localhost:6931/index.js:16767:18)
at Object.doRewind (http://localhost:6931/index.js:16814:10)
at http://localhost:6931/index.js:16838:41
at callUserCallback (http://localhost:6931/index.js:6272:3)
at http://localhost:6931/index.js:6285:3
at abort (http://localhost:6931/index.js:1516:10)
at runAndAbortIfError (http://localhost:6931/index.js:16700:3)
at Object.maybeStopUnwind (http://localhost:6931/index.js:16781:4)
at ret. (http://localhost:6931/index.js:16767:18)
at Object.doRewind (http://localhost:6931/index.js:16814:10)
at http://localhost:6931/index.js:16838:41
at callUserCallback (http://localhost:6931/index.js:6272:3)
at http://localhost:6931/index.js:6285:3
Main loop implemented with emscripten_sleep.
Any ideas or hints to solve this one?