fix(backend): preserve message in logs and use proper Winston error format

Author: drb101005

backend/logger.js

@@ -1,15 +1,16 @@
 const { createLogger, format, transports } = require('winston');
-const { combine, timestamp, printf, colorize } = format;
+const { combine, timestamp, printf, colorize, errors } = format;
 
 const logFormat = printf(({ level, message, timestamp, stack }) => {
-  return `${timestamp} ${level}: ${stack || message}`;
+  const stackTrace = stack ? `\n${stack}` : '';
+  return `${timestamp} ${level}: ${message}${stackTrace}`;
 });
 
 const logger = createLogger({
   level: process.env.LOG_LEVEL || (process.env.NODE_ENV === 'production' ? 'info' : 'debug'),
-  format: combine(timestamp(), logFormat),
+  format: combine(errors({ stack: true }), timestamp(), logFormat),
   transports: [
-    new transports.Console({ format: combine(colorize(), timestamp(), logFormat) }),
+    new transports.Console({ format: combine(errors({ stack: true }), colorize(), timestamp(), logFormat) }),
   ],
 });
 

backend/server.js

@@ -37,5 +37,5 @@ mongoose.connect(process.env.MONGO_URI, {}).then(() => {
         logger.info(`Server running on port ${process.env.PORT}`);
     });
 }).catch((err) => {
-    logger.error('MongoDB connection error', { message: err.message, stack: err.stack });
+    logger.error('MongoDB connection error', err);
 });