show an error if bin executing fails

bin/gemini-react-server

@@ -3,6 +3,7 @@
 
 const program = require('commander');
 const Gemini = require('gemini');
+const GeminiError = require('gemini/lib/errors/gemini-error');
 const pgk = require('../package.json');
 const setup = require('../lib/setup');
 
@@ -16,4 +17,5 @@ const gemini = new Gemini(program.config);
 const server = setup(gemini);
 gemini.readTests(program.args)
     .then(() => server.start())
-    .then(url => console.log(`Server is running on ${url}`));
+    .then(url => console.log(`Server is running on ${url}`))
+    .catch(err => new GeminiError(err));