improve db init

app.ts

@@ -159,14 +159,18 @@ app.post("/buy", async (req, res, next) => {
     }
 });
 
-function getDbConnection(): Promise<sql.Database> {
+function getDbConnection(): sql.Database {
 
-    return new Promise<sql.Database>((resolve, reject) => {
+    return new sql.Database(DB_FILE_NAME);
+}
+
+function initDatabase(): Promise<void>{
+    return new Promise<void>((resolve, reject) => {
         if(!fs.existsSync("./data")){
             fs.mkdirSync("data");
         };
         
-        let db = new sql.Database(DB_FILE_NAME);       
+        let db = getDbConnection();
 
         db.run(
             "CREATE TABLE IF NOT EXISTS transfers( " +
@@ -179,7 +183,7 @@ function getDbConnection(): Promise<sql.Database> {
                     reject(err);
                 }
                 else{
-                    resolve(db);
+                    resolve();
                 }
             }
         );
@@ -222,6 +226,12 @@ function errorMiddleware(err: any, req: any, res: any, next: any): void { //TODO
 
 app.use(errorMiddleware);
 
-app.listen(CHAIN4ALL_SERVICE_PORT, () => {
-    console.log(`Listening at http://localhost:${CHAIN4ALL_SERVICE_PORT}`)
+app.listen(CHAIN4ALL_SERVICE_PORT,async () => {
+    try{
+        await initDatabase();
+        console.log(`Listening at http://localhost:${CHAIN4ALL_SERVICE_PORT}`);
+    }catch(err){
+        console.error("Cannot start service!");
+        console.error(err);
+    }    
 });