-only and -json don't work together, -only fuse doesn't work at all

[quantenzitrone]

To Reproduce

json not filtering:

1. run duf -only local -json or duf -only special -json
2. observe all devices being printed in the json (for me that is special, local and fuse)

only fuse not working:

1. run duf -all
2. see some (for me one) fuse file systems
3. run duf -only fuse
4. observe nothing being printed

System Information

$ duf --version
duf 0.8.1
$ uname -a
Linux venquore 6.10.3 #1-NixOS SMP PREEMPT_DYNAMIC Sat Aug  3 07:01:09 UTC 2024 x86_64 GNU/Linux
$ nixos-version
24.11.20240811.a58bc8a (Vicuna)

[RangerCD]

duf/main.go

Line 50 in ae480f3

jsonOutput = flag.Bool("json", false, "output all devices in JSON format")

--json is supposed to print all devices

duf/groups.go

Lines 80 to 88 in ae480f3

	// skip special devices
	if v.Blocks == 0 && !*all {
	continue
	}
	// skip zero size devices
	if v.BlockSize == 0 && !*all {
	continue
	}

--only fuse shows only fuse devices, but each device also has to be a valid storage device

For example, I can see 4 fuse devices with --all, but only the first one that is actually an object storage mounted with JuiceFS can be recognized.

--all

--only fuse