preserve lts support

app.js

@@ -70,16 +70,22 @@ tty.on('disconnect', () => {
   console.log('disconnect');
 });
 
-async function loadSSL({ sslkey, sslcert }) {
-  try {
-    return sslkey && sslcert
-      ? {
-          key: await fs.readFile(path.resolve(sslkey)),
-          cert: await fs.readFile(path.resolve(sslcert)),
-        }
-      : {};
-  } catch (err) {
-    console.err(err);
-    process.exit(1);
+function loadSSL({ sslkey, sslcert }) {
+  return new Promise((resolve, reject) => {
+    if (sslkey && sslcert) {
+      const ssl = {};
+      fs
+        .readFile(path.resolve(sslkey))
+        .then(key => {
+          ssl.key = key;
+        })
+        .then(fs.readFile(path.resolve(sslcert)))
+        .then(cert => {
+          ssl.cert = cert;
+        })
+        .then(resolve(ssl))
+        .catch(reject);
     }
+    resolve({});
+  });
 }