// PDF without signature annotations works properly, use {data: pdfData} for a demonstration
var loadingTask = pdfjsLib.getDocument({data: pdfDataSigned});
loadingTask.promise.then(function(pdf) {
  console.log('PDF loaded');
  
  // Fetch the first page
  var pageNumber = 1;
  pdf.getPage(pageNumber).then(function(page) {
    console.log('Page loaded');
    page.getAnnotations().then(function(annotations) {
        // this is never executed if the page has signatures
        console.log('annotations loaded');
        for (let i = 0; i < annotations.length; i++) {
          console.log(annotations[i].subtype);
        }
      }, function (reason) {
      // this also does not happen if the page has signatures
      // Annotations loading error
      console.log(reason);
      });    
  });
}, function (reason) {
  // PDF loading error
  console.error(reason);
});