Crash in adjusting positions for folding ranges

[DanielRosenwasser]

Since #3365, this is the only failure coming from LineAndCharacterToPosition.

internal/ls/lsconv.(*Converters).LineAndCharacterToPosition()
	internal/ls/lsconv/converters.go:175
internal/ls.(*LanguageService).adjustFoldingEnd()
	internal/ls/folding.go:43
internal/ls.(*LanguageService).ProvideFoldingRange()
	internal/ls/folding.go:23
internal/lsp.(*Server).handleFoldingRange()
	internal/lsp/server.go:1267
internal/lsp.init.func1.registerLanguageServiceDocumentRequestHandler[...].28.1()
	internal/lsp/server.go:798
internal/lsp.(*Server).handleRequestOrNotification.func1()
	internal/lsp/server.go:655
internal/lsp.(*Server).dispatchLoop.func3()
	internal/lsp/server.go:523
internal/lsp.(*Server).dispatchLoop
	internal/lsp/server.go:522

[jakebailey]

that's very odd, given that implies the line map itself is wrong...

[jakebailey]

What is the actual message?

[DanielRosenwasser]

No idea - we only keep the stack around.

[DanielRosenwasser]

After some investigations, I wonder if this comes back to the snapshotfs implementation. We have two methods, reloadEntry and reloadEntryIfNeeded which have this code:

typescript-go/internal/project/snapshotfs.go

Lines 304 to 312 in cf6d69d

	if ok {
	e.Change(func(file *diskFile) {
	file.content = content
	file.hash = xxh3.HashString128(content)
	file.needsReload = false
	})
	} else {
	e.Delete()
	}

Note that lineMapOnce, lineMap, lineInfoOnce and lineInfo aren't also modified.

That said, coming up with a test case end-to-end with hasn't been entirely straightforward (nor has trying to repro it in an actual editor).