feat(logger): add warn function and refactor code

src/logger.ts

@@ -1,6 +1,11 @@
-const log = (...args: any) => console.log(`LOG:${Date.now()}`, ...args);
-const info = (...args: any) => console.info(`INF:${Date.now()}`, ...args);
-const error = (...args: any) => console.error(`ERR:${Date.now()}`, ...args);
+const doLog = (fn: Function, prefix: string, args: any) => {
+  fn(`${prefix}:${Date.now()}`, ...args);
+};
 
-export { log, info, error };
-export default { log, info, error };
+const log = (...args: any) => doLog(console.log, 'LOG', args);
+const info = (...args: any) => doLog(console.info, 'INF', args);
+const warn = (...args: any) => doLog(console.warn, 'WRN', args);
+const error = (...args: any) => doLog(console.error, 'ERR', args);
+
+export { log, info, warn, error };
+export default { log, info, warn, error };