Error handling

[lmestel]

The CLI should print some information why a command failed.

Current output is something like

node:internal/process/promises:288
            triggerUncaughtException(err, true /* fromPromise */);
            ^

[UnhandledPromiseRejection: This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason "[object Array]".] {
  code: 'ERR_UNHANDLED_REJECTION'
}