Steps to reproduce:

1. Insert burned CD (in my case it's Audio CD) into CD/DVD drive on client
2. Request key vfs.fs.get from Zabbix Agent 2

Result:
ZBX_NOTSUPPORTED: json: unsupported value: NaN

Expected:
Not sure how should Zabbix Agent 2 respond, but Zabbix Agent does not have this issue and returns:

{"fsname":"F:","fstype":"CDFS","fslabel":"Audio CD","fsdrivetype":"cdrom","bytes":{"total":0,"free":0,"used":0,"pfree":-nan(ind),"pused":-nan(ind)}}