1.21.0 Cannot read property 'attrs' of undefined

[神秘博士]

When open this pptx, an error occurred
test.pptx

pptxjs.js?v=1.21.0:869 Uncaught TypeError: Cannot read property 'attrs' of undefined
    at processGroupSpNode (pptxjs.js?v=1.21.0:869)
    at processGraphicFrameNode (pptxjs.js?v=1.21.0:8531)
    at processNodesInSlide (pptxjs.js?v=1.21.0:793)
    at processSingleSlide (pptxjs.js?v=1.21.0:712)
    at processPPTX (pptxjs.js?v=1.21.0:363)
    at convertToHtml (pptxjs.js?v=1.21.0:179)
    at Object.load (pptxjs.js?v=1.21.0:126)
    at FileReader.reader.<computed> (filereader.js?v=0.99:369)

[Tady]

fixed in v1.21.1