logger.js

const { createLogger, format, transports } = require('winston');
const { combine, timestamp, printf} = format;
const { Worker, isMainThread } = require('worker_threads');
const logFormat = printf(({ level, message, timestamp }) => {
  return `{ "Date": "${timestamp}", "level": "${level.toUpperCase()}",  "message": "${message}" }`;
});


class Logger {
 log(message, logType=null) {
      if (isMainThread && !this.thread) {
          this.thread = new Worker(__filename);
      }   
      this.getLogger(message)
      switch(logType){
        case "error":
          this.getLogger().error(message);
          break;
        case "info":
          this.getLogger().info(message);
          break;
        case "warn":
          this.getLogger().warn(message);
          break;
        default:
          this.getLogger
      }
 }

  getLogger() {
    if (!this.logger) {
      if (process.env.NODE_ENV !== 'production') {
          this.logger = createLogger({
            transports: [
              new transports.Console({
                format: combine(
                  timestamp(),
                  logFormat,
                ),
              })
            ]
          });
    } else {
          this.logger = createLogger({
            transports: [
              new transports.File({
                filename: 'error.log',
                format: combine(
                  timestamp(),
                  logFormat,
                ),
              })
            ]
          });
    }

    }

    return this.logger;
  }
}

exports.Logger = Logger;

line 10 needs one indentation

this.logger = createLogger({
        transports: [
          new transports.Console({
            format: combine(
              timestamp(),
              logFormat,
            ),
          })
        ]
      });

Needs indentation