Ionic PDFMake throws error when swtiching between pages after PDF generation

I am using PDFMake, library to generate PDF from my ionic/angular application. The PDF generation is working perfectly fine. However issue is that -

1. After pdf generation process is completed, I go back to dashboard page
2. And from dashboard page I go to Another page (any page, same pdf generation page or any other page), I get following error.

I have following codes:

import pdfMake from 'pdfmake/build/pdfmake';
import pdfFonts from 'pdfmake/build/vfs_fonts';
pdfMake.vfs = pdfFonts.pdfMake.vfs;

//---------------------
//---------------------

ionViewWillLeave(){
    if(this.pdfObj) this.pdfObj = null;
}

generatePdf(){
    let docDefinition = {
      pageSize: "A3",
      content: [
        ..............
      ],
    }

    this.pdfObj = pdfMake.createPdf(docDefinition);
    this.pdfObj.download();
}
  ------------------------------------

Any help will be highly appreciated.

Thanks