const watermark = require('image-watermark');
const imagePath = path.resolve(__dirname,'./relative/path/to/image');
watermark.embedWatermarkWithCb(imagePath, { 'text': 'sample watermark' },
function (err) {
    if (!err)
      console.log('Succefully embeded watermark');
    else {
      //I am getting error here.
      console.log(err);
    }
});

{ Error: Command failed:
    at ChildProcess.<anonymous>(...node_modulesimagemagickimagemagick.js:88:15)
    at emitTwo (events.js:131:20)
    at ChildProcess.emit (events.js:214:7)
    at maybeClose (internal/child_process.js:925:16)
    at Process.ChildProcess._handle.onexit
(internal/child_process.js:209:5) timedOut: false, killed: false, code: 1,
signal: null }