diff --git a/web/scripts/check-bundle-size.mjs b/web/scripts/check-bundle-size.mjs
index 65105ef..cb3364e 100644
--- a/web/scripts/check-bundle-size.mjs
+++ b/web/scripts/check-bundle-size.mjs
@@ -6,6 +6,10 @@ import { join } from "node:path";
 const BUDGET_KB = 150;
 const dir = "dist/assets";
 const jsFiles = readdirSync(dir).filter((f) => f.endsWith(".js"));
+if (jsFiles.length === 0) {
+  console.error(`no JS files found in ${dir} — was the build skipped?`);
+  process.exit(1);
+}
 let largest = 0;
 let largestName = "";
 for (const file of jsFiles) {