Update Karma to latest, make errors more helpful

[trusktr]

See if newer Karma makes error reporting better (it currently omits stack traces in some cases, which requires going on a bug hunting safari each time). See karma-runner/karma#3296

To test a difficult-to-debug error, checkout commit bc435fcef9320f4c20c9802f94ef71f7667cef87 of the lume/lume repo (recursively including sub modules).

Also see the try-to-improve-error-output branch here in cli, to see if we can improve the console logging.