Fix canvas pdf to csv

[DimK10]

Description

Please provide a summary of the changes, including relevant motivation and context.

Closes #2227

Checklist

• I have read the Contribution Guidelines
• I have performed a self-review of my own code
• [] I have attached images of the change if it is UI based
• I have commented my code, particularly in hard-to-understand areas
• [] If my code has heavily changed functionality I have updated relevant docs on Stirling-PDFs doc repo
• My changes generate no new warnings
• [] I have read the section Add New Translation Tags (for new translation tags only)