PDF generation fails if HTML contains invalid markup

[JaneSjs]

Double <br><br> tags

• T11254 - GeneratePDF not working
  https://surveyjs.answerdesk.io/internal/ticket/details/T11254
• T12822 - PDF generation issues
  https://surveyjs.answerdesk.io/internal/ticket/details/T12822
• T14035 - How to use the
  tag in HTML survey correctly?
  https://surveyjs.answerdesk.io/internal/ticket/details/T14035
• T15547 - Error exporting PDF - TypeError: Cannot read properties of undefined (reading '1')
  https://surveyjs.answerdesk.io/internal/ticket/details/T15547
• T10702 - Export PDF Problem
  https://surveyjs.answerdesk.io/internal/ticket/details/T10702
• T16489 - Html-Element with two
  -Tags fails to generate a pdf
  https://surveyjs.answerdesk.io/internal/ticket/details/T16489
• T16576 - Export to PDF with markdown crashes on empty lines
  https://surveyjs.answerdesk.io/internal/ticket/details/T16576

Special single quotes

• T12538 - Special characters are messing up rendered text when exporting PDF
  https://surveyjs.answerdesk.io/internal/ticket/details/T12538

[JaneSjs]

The PDF generation still fails when HTML contains double tags:
T20869 - PDF Generator doesn't work for HTML block
https://surveyjs.answerdesk.io/internal/ticket/details/T20869