ERROR TypeError: this.x.toFixed is not a function at CanvasWhiteboardUpdate.stringify (ng2-canvas-whiteboard.js:61)

[kpratikoc]

const historyUpdates: Array<CanvasWhiteboardUpdate> = this.CanvasWhiteboardComponent.getDrawingHistory();

Getting the above error while getting the array of string from the drawingHistory.
on this line of code: ** this.historyUpdates.map(update => update.stringify()) ;**

  // Stringify the updates, which will return an Array<string>
      const stringifiedUpdatesArray: Array<string> = this.historyUpdates.map(update => update.stringify());

[kpratikoc]

@Peshou do you have any idea on this. I am stuck and need your help. thanks