Fixing the --render option

The promisified version of index.getShortIndex() was not used.

Author: agnivade

lib/tldr.js

@@ -56,16 +56,20 @@ exports.randomExample = () => {
 };
 
 exports.render = (file) => {
-  // Reading the file
   fs.readFile(file, 'utf8', (err, content) => {
     if (err) {
       console.error(err);
       exit(1);
     }
     // Getting the shortindex first to populate the shortindex var
-    index.getShortIndex(() => {
-      renderContent(content);
-    });
+    index.getShortIndex()
+      .then(() => {
+        renderContent(content);
+      })
+      .catch((err) => {
+        console.error(err);
+        exit(1);
+      });
   });
 };
 
@@ -166,7 +170,7 @@ function printBestPage(command, options={}) {
   });
 }
 
-function renderContent(content, options) {
+function renderContent(content, options={}) {
   if (options.markdown) {
     return console.log(content);
   }