Fix Uncaught TypeError: Cannot read property 'update' of undefined (#567)
Fix Uncaught TypeError: Cannot read property 'update' of undefined (#567)

Closes #539.
michaelgeorgeattard/webtorrent-desktop,feross/webtorrent-app,feross/webtorrent-desktop,feross/webtorrent-app,feross/webtorrent-desktop,webtorrent/webtorrent-desktop,webtorrent/webtorrent-desktop,yciabaud/webtorrent-desktop,feross/webtorrent-desktop,michaelgeorgeattard/webtorrent-desktop,webtorrent/webtorrent-desktop,michaelgeorgeattard/webtorrent-desktop,feross/webtorrent-app,yciabaud/webtorrent-desktop,yciabaud/webtorrent-desktop