return 200 and piston ver on /, fix empty content-type header validation

api/src/index.js

@@ -79,6 +79,12 @@ expressWs(app);
     const api_v2 = require('./api/v2');
     app.use('/api/v2', api_v2);
 
+    const { version } = require('../package.json');
+
+    app.get('/', (req, res, next) => {
+        return res.status(200).send({ message: `Piston v${version}` });
+    });
+
     app.use((req, res, next) => {
         return res.status(404).send({ message: 'Not Found' });
     });