Comment 2 for bug 1831527

So I got focused on this and am going to propose a fix soon.

The reason that you are seeing it is due to timing and using -t 0 highlights it.
This 'not found' error is not actually an error in this case (hence, the operation succeeds). It happens because we attempt to destroy all Juju side first which involves removing machines and their instances and then without waiting for the completion (because we've specified -t 0), we attempt to destroy cloud instances. In other words, we try to destroy cloud instances twice, almost at the same time, and there is a greater potential that we'd get some instances listed for destruction but they are being marked for destruction at the same time.

The code does try to cater for this and does have a code path that ignores 'not found' errors. Unfortunately, the check that inspects errors is not correct for GCE errors. And this is the bit that I'll correct - this will stop notifying users of errors that are not actually relevant.

I'll also double-check other providers to ensure that similar behavior works.