Editor node.js file upload example error - A server error occurred while uploading the file

Editor node.js file upload example error - A server error occurred while uploading the file

I'm not getting the basic file upload example to run:

https://editor.datatables.net/manual/nodejs/upload

In the frontend I'm getting:

A server error occurred while uploading the file

... when trying to upload a file.

let {
    Editor,
    Field,
    Validate,
    Format,
    Options,
    Upload,
    promisify
} = require('datatables.net-editor-server');

let unlink = promisify(fs.unlink); // await version of unlink

var getBody = JSON.parse(req.body.json);

let editor = new Editor( db, 'news', 'id' )
.fields(
  new Field( 'news.id', 'id' ),
  new Field( 'news.cruser_id', 'cruser_id' ),
  new Field( 'news.image', 'image' ).setFormatter( Format.ifEmpty(null) ).upload(
      new Upload( __dirname + '/../public/uploads/{id}.{extn}' )
        .db('image', 'id', {
            fileName: Upload.Db.FileName,
            fileSize: Upload.Db.FileSize,
            web_path: '/uploads/{id}.{extn}',
            system_path: Upload.Db.SystemPath
        })
        .validator( Validate.fileSize(500000, 'Files must be smaller than 500K') )
                .validator(
                    Validate.fileExtensions(
                        ['png', 'jpg', 'gif'],
                        'Only image files can be uploaded (png, jpg and gif)'
                    )
                )
        .dbClean(async function(data) {
            for (let i = 0, ien = data.length; i < ien; i++) {
                await unlink(data[i].system_path);
            }
            return true;
        })
    )
)

await editor.process(getBody, req.files);

res.json(editor.data());

What am I missing and How can I solve this?