use template needs to work also with starter template

[cderv]

quarto use template can be used to copy files from a remote even if it does not have extension

Tweaks from #8764 regarding installation of extension only needs to happen if there is an _extension folder

#8764 uses

quarto-cli/src/command/use/commands/template.ts

Lines 83 to 104 in 0ba1c27

	// Compute extensions that need to be installed (and confirm any)
	// changes
	const extDir = join(stagedDir, kExtensionDir);
	// Determine whether we can update extensions
	const templateExtensions = await readExtensions(extDir);
	const installedExtensions = [];
	let installExtensions = false;
	if (templateExtensions.length > 0) {
	installExtensions = await confirmInstallation(
	templateExtensions,
	outputDirectory,
	{
	allowPrompt: options.prompt !== false,
	throw: true,
	message: "The template requires the following changes to extensions:",
	},
	);
	if (!installExtensions) {
	return;
	}
	}

This PR makes sure that readExtensions returns empty list when extensionsDirectory doesn't exists. This should prevent any similar issue when using readExtensions in the future.

closes #9256

I did not add to changelog because it was only broken by #8764 merged in 1.5.15

[cscheid]

Looks good. I searched for additional instances of using extensionsDirectory and this seemed to be the only one.

[cderv]

This would be readExtensions() usage maybe to look for.

I am seeing some occurrences where we externally do the existence-checking

quarto-cli/src/extension/extension.ts

Lines 694 to 697 in 0ba1c27

	// Read any embedded extension
	const embeddedExtensions = existsSync(join(extensionDir, kExtensionDir))
	? await readExtensions(join(extensionDir, kExtensionDir))
	: [];

quarto-cli/src/extension/install.ts

Lines 388 to 393 in 0ba1c27

	const existingExtensionsDir = join(installDir, kExtensionDir);
	if (Deno.statSync(existingExtensionsDir).isDirectory) {
	const existingExtensions = await readExtensions(
	join(installDir, kExtensionDir),
	);
	return existingExtensions;

Looking deeper we do have this helper

quarto-cli/src/extension/install.ts

Lines 610 to 624 in 0ba1c27

	// Is this _extensions or does this contain _extensions?
	const extensionDir = (path: string) => {
	if (basename(path) === kExtensionDir) {
	// If this is pointing to an _extensions dir, use that
	return path;
	} else {
	// Otherwise, add _extensions to this and use that
	const extDir = join(path, kExtensionDir);
	if (existsSync(extDir) && Deno.statSync(extDir).isDirectory) {
	return extDir;
	} else {
	return path;
	}
	}
	};

But it was modified not to return undefined (53ef1d9), which seems odd to me as we still checked for it in some places and it makes more sense 🤔

Anyhow, I am thinking now that this fix should probably be more scoped to template.ts by just reading if the dir exists

Or I should check all call to readExtensions()

[cderv]

Or I should check all call to readExtensions()

I went with that, aiming at cleaning some part of our code with some refactoring.