Handle access denied errors

[pimterry]

If a user doesn't have access to read some registry keys, they can get a synchronous error, which is unhandled, and which thus crashes the process. See httptoolkit/httptoolkit#50 for an example.

Imo, in this case we should just ignore the information from that registry key, and move on, rather than failing entirely. It's safe to do so I believe, it just reduces the amount of info (e.g. uninstaller paths) we can return.

I'm happy to open a PR for this, just checking it would be welcomed first. My suggestion would be to just change enumerateValues to enumerateValuesSafe, which automatically returns [] if any registry values can't be read. I've given this a quick test locally and it seems to work very nicely, and still detects other browser info as normal. Sound good?

[vweevers]

I wasn't aware enumerateValuesSafe existed! Let's use it.

(As for your other PR, I'll have a look tomorrow)

[vweevers]

Fixed by #65.