Infact this not only is the case for this item but alot of others so it might be a bigger thing. But small steps after another imo.

Steps to reproduce:

1. create item with vfs.dir.size for non-existing directory

Result:

ZBX_UNSUPPORTED : Cannot obtain directory information: [2] No such file or directory

Expected:

While the message as such IS correct the state shouldn't be ZBX_UNSUPPORTED. We monitor our proxy/server unsupported items metric as this might indicate problems. But in this cases it produces false-positve alarms all along.

A better way handling this imo would be returning a -1 if the directory is absent for example. In this case it even would be possible to use a trigger on -1 to see if the dir is absent/present.