panic while running gazelle update-repos with prune

[voxeljorge]

What version of gazelle are you using?

0.25

What version of rules_go are you using?

0.32.0

What version of Bazel are you using?

Bazelisk version: v1.11.0 Build label: 5.1.1 Build target: bazel-out/k8-opt/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar Build time: Fri Apr 8 15:49:48 2022 (1649432988) Build timestamp: 1649432988 Build timestamp as int: 1649432988

Does this issue reproduce with the latest releases of all the above?

I believe I am on the latest releases

What operating system and processor architecture are you using?

linux/amd64

What did you do?

I ran a rule which should run gazelle update-repos which looks like this:

gazelle(
    name = "gazelle-update-repos",
    args = [
        "-from_file=go.mod",
        "-to_macro=go_deps.bzl%go_dependencies",
        "-prune",
    ],
    command = "update-repos",
)

What did you expect to see?

Bazel should have updated go depedencies and exited successfully

What did you see instead?

Bazel panics with the following:

panic: runtime error: index out of range [4] with length 1

goroutine 1 [running]:
github.com/bazelbuild/bazel-gazelle/rule.byName.Swap(...)
	external/bazel_gazelle/rule/rule.go:510
sort.insertionSort({0x4d4b988, 0xc00019ff80}, 0x0, 0x12)
	GOROOT/src/sort/sort.go:41 +0x64
sort.stable({0x4d4b988, 0xc00019ff80}, 0x12)
	GOROOT/src/sort/sort.go:390 +0x70
sort.Stable({0x4d4b988, 0xc00019ff80})
	GOROOT/src/sort/sort.go:379 +0x39
github.com/bazelbuild/bazel-gazelle/rule.(*File).SortMacro(0xc0002a28c0)
	external/bazel_gazelle/rule/rule.go:399 +0xb4
main.updateRepos({0xc00003001a, 0x1a}, {0xc000128020, 0x3, 0x3})
	external/bazel_gazelle/cmd/gazelle/update-repos.go:293 +0x1fc9
main.run({0xc00003001a?, 0x1a?}, {0xc000128010?, 0x4?, 0x4?})
	external/bazel_gazelle/cmd/gazelle/gazelle.go:99 +0x1d8
main.main()
	external/bazel_gazelle/cmd/gazelle/gazelle.go:72 +0xdd

I noticed that if I remove -prune gazelle works correctly. Seems like a bug? I'm new to both Bazel and Gazelle, so this could be user error but as there is a panic here I suspect that at a minimum some bounds checking is missing here.