Add resubscribeInvoices call and refactorize code

- Async functions, like `resubscribeInvoices` cannot be called inside a
  synchronous function, as the former server loop.

Author: csralvall

app.js

@@ -1,10 +1,19 @@
 require('dotenv').config();
 const { start } = require('./bot');
 const mongoConnect = require('./db_connect');
+const { resubscribeInvoices } = require('./ln');
 
-process.on('unhandledRejection', e => { console.log (e); });
+(async () => {
+    process.on('unhandledRejection', e => { console.log (e); });
 
-process.on('uncaughtException', e => { console.log (e); });
+    process.on('uncaughtException', e => { console.log (e); });
 
-mongoConnect();
-start(process.env.BOT_TOKEN);
+    mongoose = mongoConnect();
+    mongoose.connection
+    .once('open', async () => {
+        console.log('Connected to Mongo instance.');
+        const bot = start(process.env.BOT_TOKEN);
+        await resubscribeInvoices(bot);
+    })
+    .on('error', error => console.log('Error connecting to Mongo:', error))
+})();

bot/start.js

@@ -722,9 +722,13 @@ const start = (botToken) => {
 
   bot.launch();
 
+  console.log('Bot launched.');
+
   // Enable graceful stop
   process.once('SIGINT', () => bot.stop('SIGINT'));
   process.once('SIGTERM', () => bot.stop('SIGTERM'));
+
+  return bot;
 };
 
 module.exports = { initialize, start };

db_connect.js

@@ -12,9 +12,7 @@ const connect = () => {
     useNewUrlParser: true,
     useUnifiedTopology: true,
   });
-  mongoose.connection
-    .once('open', () => console.log('Connected to Mongo instance.'))
-    .on('error', error => console.log('Error connecting to Mongo:', error));
+  return mongoose
 };
 
 module.exports = connect;