Add validation scripts

Make sure that all samples are listed properly and the readme is updated

.scripts/validate.js

@@ -0,0 +1,43 @@
+// @ts-check
+const path = require('path');
+
+const { samples, lspSamples } = require('./samples');
+const fs = require('fs');
+
+const root = path.join(__dirname, '..');
+
+/**
+ * Validates that all samples are correctly listed in `.scripts/samples.js`.
+ */
+function validateSamplesAreListed() {
+	const allSamples = samples.concat(lspSamples);
+
+	const samplesByPath = new Map();
+	for (const sample of allSamples) {
+		samplesByPath.set(sample.path, sample);
+	}
+
+	for (const fileName of fs.readdirSync(root)) {
+		if (!fileName.endsWith('-sample') || fileName.startsWith('.')) {
+			continue;
+		}
+
+		const sampleEntry = samplesByPath.get(fileName);
+		if (!sampleEntry) {
+			throw new Error(`Sample '${fileName}' is not listed in samples.js`);
+		}
+	}
+}
+
+/**
+ * Validates that all samples are correctly listed in `.scripts/samples.js`.
+ */
+function validateReadmeUpdated() {
+	const { updateReadme } = require('./update-readme');
+	if (updateReadme(true)) {
+		throw new Error(`Readme not updated. Run 'node .scripts/update-readme.js' to update the readme.`);
+	}
+}
+
+validateSamplesAreListed();
+validateReadmeUpdated();