Thanks for the reports. Here is a new version with the following changes:
- Fixed the exception reported above. I missed a few calls in the reading position dialog since I haven't used it myself, and the way the dialog code works the call sites didn't show up for me in a search for callers of the function I changed for the additional columns.
- Fixed the issue that @ownedbycats reported, where unchecking a book in the reading position dialog didn't work.
- There is now no dialog popup if there are no reading position changes, even if you have enabled the "Prompt for changes" option.
I hope this takes care of the important issues that are relevant for a new release.