The errors in `teardown` are not being reported

https://github.com/ipfs/go-ipfs/blob/c17aaa6e26512b6bbd0f60c0c39c82daacfba9e1/core/core.go#L712-L722

I don't quite follow the return path of the errors of this function (that are indeed being returned, at least the first one) but while digging into an MFS issue I've found that an error in the MFS `Close` method was not being showed in the console of the daemon (even with the debug flag).

I haven't completely identified the MFS error itself so I can't provide an exact way to reproduce this, the closest so far is:

```
# Console 1:
ipfs daemon -D

# Console 2:
ipfs files write --create --flush=false /file <<