Problem: can't export to pdf

[mantramatt]

Testing a large MD file with mermaid diagrams and code snippets (approx 120 pages)

File displays correctly an error is produced in the console when Exporting to PDF. The UI reports the PDF is exported, however, no file is downloaded.

Uncaught (in promise) Error: Font 'Monospace' in style 'normal' is not defined in the font section of the document definition.
    at FontProvider.provideFont (fontProvider.js:52:9)
    at textTools.js:326:27
    at Array.forEach (<anonymous>)
    at measure (textTools.js:298:13)
    at TextTools.buildInlines (textTools.js:32:17)
    at DocMeasure.measureLeaf (docMeasure.js:238:28)
    at docMeasure.js:59:30
    at StyleContextStack.auto (styleContextStack.js:102:15)
    at DocMeasure.measureNode (docMeasure.js:44:25)
    at DocMeasure.measureVerticalContainer (docMeasure.js:292:19)
    at docMeasure.js:51:30
    at StyleContextStack.auto (styleContextStack.js:102:15)
    at DocMeasure.measureNode (docMeasure.js:44:25)
    at DocMeasure.measureVerticalContainer (docMeasure.js:292:19)
    at docMeasure.js:51:30
    at StyleContextStack.auto (styleContextStack.js:102:15)
    at DocMeasure.measureNode (docMeasure.js:44:25)
    at DocMeasure.measureVerticalContainer (docMeasure.js:292:19)
    at docMeasure.js:51:30
    at StyleContextStack.auto (styleContextStack.js:102:15)
    at DocMeasure.measureNode (docMeasure.js:44:25)
    at DocMeasure.measureDocument (docMeasure.js:37:14)
    at LayoutBuilder.tryLayoutDocument (layoutBuilder.js:150:33)
    at LayoutBuilder.layoutDocument (layoutBuilder.js:137:20)
    at PdfPrinter.createPdfKitDocument (printer.js:153:22)
    at pdfMake.js:133:21Understand this error