So Kindle.app was updated through the App Store and did not start any more. It just crashed and the crash reporter came up.
A quick look at Console.app turns up a link to the actual crash report. And the crash report starts with
Dyld Error Message: Library not loaded: @executable_path/../Frameworks/libWEbCoreKRF.dylib Referenced from: /Applications/Kindle.app/Contents/Frameworks/libWebCoreViewer.dylib Reason: image not found
libWEbCoreKRF.dylib? With a capitalized
E? That looks very much like a spelling error. So, point your terminal to
sudo ln -s libWebCoreKRF.dylib libWEbCoreKRF.dylib
to create a symlink with the misspelled name. Done.
Kindle works again.
Spelling is hard, it seems.