renderer: fix panic on unregistered node kind

[emersion]

Renderers can ignore nodes they aren't interested in. However when a
renderer doesn't register the highest node kind traversing a Markdown
document results in the following panic:

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

goroutine 1 [running]:
github.com/yuin/goldmark/renderer.(*renderer).Render.func2({0x9d8630, 0xc0001237a0}, 0x40?)
	/home/simon/go/pkg/mod/github.com/yuin/[email protected]/renderer/renderer.go:164 +0xd9
github.com/yuin/goldmark/ast.walkHelper({0x9d8630, 0xc0001237a0}, 0xc000521a48)
	/home/simon/go/pkg/mod/github.com/yuin/[email protected]/ast/ast.go:492 +0x34
github.com/yuin/goldmark/ast.Walk(...)
	/home/simon/go/pkg/mod/github.com/yuin/[email protected]/ast/ast.go:487
github.com/yuin/goldmark/renderer.(*renderer).Render(0xc0002d80a0?, {0x9d3b60?, 0xc0000744a0?}, {0xc0002f4580?, 0x281?, 0x2c0?}, {0x9d8630?, 0xc0001237a0?})
	/home/simon/go/pkg/mod/github.com/yuin/[email protected]/renderer/renderer.go:161 +0x225
github.com/yuin/goldmark.(*markdown).Convert(0xc0001e1d40, {0xc0002f4580, 0x281, 0x2c0}, {0x9d3b60, 0xc0000744a0}, {0x0, 0x0, 0x0})
	/home/simon/go/pkg/mod/github.com/yuin/[email protected]/markdown.go:117 +0x10b
main.renderMarkdown({0xc0002f42c0, 0x281})
	/home/simon/src/hut/markdown.go:16 +0x97
main.newListsListCommand.func1(0xc000270280?, {0xc778b8, 0x0, 0x0?})
	/home/simon/src/hut/lists.go:109 +0x2ee
github.com/spf13/cobra.(*Command).execute(0xc000270280, {0xc778b8, 0x0, 0x0})
	/home/simon/go/pkg/mod/github.com/spf13/[email protected]/command.go:860 +0x663
github.com/spf13/cobra.(*Command).ExecuteC(0xc000242c80)
	/home/simon/go/pkg/mod/github.com/spf13/[email protected]/command.go:974 +0x3b4
github.com/spf13/cobra.(*Command).Execute(...)
	/home/simon/go/pkg/mod/github.com/spf13/[email protected]/command.go:902
github.com/spf13/cobra.(*Command).ExecuteContext(...)
	/home/simon/go/pkg/mod/github.com/spf13/[email protected]/command.go:895
main.main()
	/home/simon/src/hut/main.go:49 +0x30b

Make sure r.nodeRendererFuncs is large enough before trying to access it.

Workaround without this patch:

reg.Register(ast.NodeKind(128), nil)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[emersion]

Ping

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[emersion]

Ping

[emersion]

@yuin any chance to get this reviewed?

[MarceloLimoriGM2dev]

I was about to write a new bug report for this. So ping! from me too.

[abhinav]

FWIW, this has come up before.

#107 made a similar change to this PR, removing the panic, but the behavior change was considered undesirable.

Following that, #110 and #166 made a variant of the change that kept the panic but improved the error message.

@yuin, would you be open to merging the message change?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[emersion]

Ping

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[emersion]

.

[github-actions]

This PR is stale because it has been open for 180 days with no activity.

[emersion]

.

[github-actions]

This PR is stale because it has been open for 180 days with no activity.

[emersion]

.