E-book viewer - Error: Unhandled error

[Richard Scriven]

On opening a old ebook in the e-book viewer i get the following error and the viewer stalls. I downloaded a new version of the book, same; converted the book still gives the same error. I checked the book in the editor and it shows no errors.

 Error: Unhandled error
Uncaught TypeError: Cannot read property 'length' of null
Error at userscript:viewer.js:13471:43
Traceback (most recent call last):
    at Number.onload (userscript:viewer.js:12149:21)
    at IframeBoss.content_loaded (userscript:viewer.js:17476:18)
    at IframeBoss.content_loaded_stage2 (userscript:viewer.js:17493:26)
    at IframeBoss.scroll_to [as jump_to_cfi] (userscript:viewer.js:13520:22)
    at point (userscript:viewer.js:13471:43)
TypeError: Cannot read property 'length' of null

Calibre 4.1
Windows 10 home v1903

[Kovid Goyal (kovid)]

Fixed in branch master. The fix will be in the next release. calibre is usually released every alternate Friday.

 status fixreleased