message: return code 1 on error in lume run
diff: @@ -32,5 +32,10 @@ export async function run(args) {
  const site = await buildSite(options);
  console.log("");
  - site.run(script);
  +
  + const success = await site.run(script);
  +
  + if (!success) {
  + window.addEventListener("unload", () => Deno.exit(1));
  + }
  }
  