Tor process crashes

When enabling/disabling the Tor plugin in quick succession one sometimes can get the Tor process to exit.

There's two ways that have been observed so far:

The first one prints an exception whenever trying to make control commands:

W/TorPlugin: java.io.IOException: Tor is no longer running
    java.io.IOException: Tor is no longer running
at net.freehaven.tor.control.TorControlConnection.react(TorControlConnection.java:325)

The second one doesn't print anything to the log. The TorPlugin seems to hang (only prints on the event thread) and signing out of Briar isn't possible anymore. It just hangs at the sign out fragment.