Warning if /tmp has no free space

[levu42]

If there is no free space in the tmp-directory packer is using, the only error you get is "curl(23) Failed writing body (X != Y)" with X and Y being numbers. Is it possible for packer to give a warning if there is no free space left? Maybe check it at least when packer is started, it doesn't have to checked all the time while packer is downloading files…