Update Checks: Better catch if WinSparkle isn't loaded/set up

[Athanasius]

Due to the playing around with 64-bit builds I'd somehow managed to leave the "used for builds" version of the GH windows-build workflow using the 64-bit version of WinSparkle.dll, although we're still using 32-bit Python.

The symptom of this is:

1. self.updater: Optional[ctypes.CDLL] = ctypes.cdll.WinSparkle fails, raising an exception.
2. No notification is given to the user.
3. No check for updates will work, or given an error, be it timed or manual.

So, we really need to be more paranoid in this code. There's a try/except already, but all the latter does is log the exception and then continue. We should be popping up an alert instead and after it's closed exit the program.