add passing 404 test (cov 85%)

Author: juliangruber

test/index.js

@@ -27,5 +27,8 @@ test('Updates', async t => {
   t.ok(body.name)
   t.match(body.url, /-mac\.zip$/)
 
+  res = await fetch(`${address}/juliangruber/brace-expansion/darwin/0.0.0`)
+  t.equal(res.status, 404)
+
   server.close()
 })