only run postinstall if package.json exists (#6998)

* only run postinstall if package.json exists - closes #6987

* Update packages/kit/postinstall.js

Co-authored-by: Simon H <[email protected]>

* belt and braces

* accommodate yarn's... idiosyncracies

Co-authored-by: Simon H <[email protected]>

Author: Rich-Harris

.changeset/hungry-flowers-hope.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Only run postinstall script if package.json exists

packages/kit/postinstall.js

@@ -4,35 +4,44 @@ import glob from 'tiny-glob/sync.js';
 import { load_config } from './src/core/config/index.js';
 import * as sync from './src/core/sync/sync.js';
 
-const cwd = process.env.INIT_CWD ?? process.cwd();
-process.chdir(cwd);
+try {
+	const cwd = process.env.INIT_CWD ?? process.cwd();
+	process.chdir(cwd);
 
-const pkg = JSON.parse(fs.readFileSync('package.json', 'utf8'));
+	if (fs.existsSync('package.json')) {
+		const pkg = JSON.parse(fs.readFileSync('package.json', 'utf8'));
 
-const directories = [];
+		const directories = [];
 
-if (pkg.workspaces) {
-	for (const directory of pkg.workspaces) {
-		directories.push(...glob(directory, { cwd }).map((dir) => path.resolve(cwd, dir)));
-	}
-} else {
-	directories.push(cwd);
-}
+		if (pkg.workspaces) {
+			// we have to do this because of https://classic.yarnpkg.com/blog/2018/02/15/nohoist/
+			const packages = Array.isArray(pkg.workspaces) ? pkg.workspaces : pkg.workspaces.packages;
 
-for (const cwd of directories) {
-	process.chdir(cwd);
+			for (const directory of packages) {
+				directories.push(...glob(directory, { cwd }).map((dir) => path.resolve(cwd, dir)));
+			}
+		} else {
+			directories.push(cwd);
+		}
+
+		for (const cwd of directories) {
+			process.chdir(cwd);
 
-	if (!fs.existsSync('package.json')) continue;
-	if (!fs.existsSync('svelte.config.js')) continue;
+			if (!fs.existsSync('package.json')) continue;
+			if (!fs.existsSync('svelte.config.js')) continue;
 
-	const pkg = JSON.parse(fs.readFileSync('package.json', 'utf8'));
-	if (!pkg.dependencies?.['@sveltejs/kit'] && !pkg.devDependencies?.['@sveltejs/kit']) continue;
+			const pkg = JSON.parse(fs.readFileSync('package.json', 'utf8'));
+			if (!pkg.dependencies?.['@sveltejs/kit'] && !pkg.devDependencies?.['@sveltejs/kit']) continue;
 
-	try {
-		const config = await load_config();
-		await sync.all(config, 'development');
-	} catch (e) {
-		console.log('Error while trying to sync SvelteKit config');
-		console.log(e);
+			try {
+				const config = await load_config();
+				await sync.all(config, 'development');
+			} catch (error) {
+				console.log('Error while trying to sync SvelteKit config');
+				console.log(error.stack);
+			}
+		}
 	}
+} catch (error) {
+	console.error(error.stack);
 }