NPM node-sprite-generator module is not generating an image when packaged in Electron app running on test Mac

firstly I'd like to say happy Friday!!

I have an issue with a NPM module (node-sprite-generator) where the Electron app that it is bundled in does not generate a sprite sheet image.

It works locally, and works when bundled and run locally. However when I run it on a different Mac (the test machine). The image is not generated.

The temporaryVideoDirectory variable is an 'app-root-dir' file path which is correct and points to the absolute path inside the Electron app.

var n = new nsg({
        src: getImagePaths(temporaryVideoDirectory, videoFrameCount),
        spritePath : temporaryVideoDirectory +'/sprite.png',
        layout : 'block'
        },
        function (error) {
            /*if(error) {
                throw error;
            }*/
            if(error.msg) {
                return callBackFunction(error.msg, 1);
            }
            setTimeout(function(){
                //console.log('Sprite generated!');
                spritesheetFilePath = temporaryVideoDirectory +'/sprite.png';
                return callBackFunction(null, 1);
            }, 5000);       
            command.kill();
        });

via Berni