Getting ERR_HTTP_INVALID_STATUS_CODE instead of the actual error

I wrote an error handler like this:
AppError class:

const getStatus = (statusCode) => {
if (statusCode >= 400 && statusCode < 500) return "fail";
return "error";
};

export class AppError extends Error {
 constructor(message, statusCode) {
  super(message);
  this.statusCode = statusCode;
  this.status = getStatus(statusCode);

  this.isOperational = true;

  Error.captureStackTrace(this, this.constructor);
 }
}

and this is some of the error handler:

const sendErrorDev = (err, req, res) => {
  console.log("dev", err);
  return res.status(err.statusCode ?? 500).json({
    status: err.status,
    error: err,
    message: err.message,
    stack: err.stack,
  });
};

const globalErrorHandler = (err, req, res, next) => {
  console.log("Caught Error:", err.statusCode);
  err.statusCode = err.statusCode || 500;
  err.status = err.status || "error";

  if (process.env.NODE_ENV === "development") {
    console.log("env", process.env.NODE_ENV);
    sendErrorDev(err, req, res);
  } else if (process.env.NODE_ENV === "production") {
    let error = cloneError(err);

    // Map known error types
    error = handleError(error);

    // MongoDB duplicate key errors (code 11000)
    if (error.code === 11000) error = handleDuplicateFieldDB(error);

    sendErrorProd(error, req, res);
  }
};

export default globalErrorHandler;

I am using this for login and I send the error like this:

  if (!user || !(await user.correctPassword(password, user.password))) {
    return next(new AppError("Incorrect email or password", 401));
  }

I get an error in postman 500 Internal Server Error

"status": "error",
"error": {
    "code": "ERR_HTTP_INVALID_STATUS_CODE",
    "statusCode": 500,
    "status": "error"
},
"message": "Invalid status code: fail",
"stack": "RangeError [ERR_HTTP_INVALID_STATUS_CODE]: Invalid status code: failn 

The env is a dev env. The err.statusCode and err.status are for some reason undefined in the globalErrorHandler.
If I change the this.status in the AppError to 401 (this.status=401) I get my error but the error in postman remains 500 Internal Server Error and the err.status and err.statusCode are not printed from globalErrorHandler so it doesn’t even enter the function.
I am very confused, please help.
Thank you