When splitting any image and exporting as PNGs through Image > Image Split, I get: Krita has encountered an internal error: SAFE ASSERT (krita): "!sanityCheckPointer.isValid()" in file /home/appimage/workspace/Krita_Release_Appimage_Build/krita/libs/ui/KisDocument.cpp, line 504 Please report a bug to developers! Hitting "Ignore" leads to the same assertion several times (one per exported frame), but the export appears to be correct. Hope this helps!
I have also faced this. In order to reproduce, just follow the instructions from the documentation for splitting image: https://docs.krita.org/en/user_manual/animation.html#importing-animation-frames I am running the krita-4.1.1-x86_64.appimage on Ubuntu 18.04. Text from UI: Krita has encountered an internal error: SAFE ASSERT (krita): "!sanityCheckPointer.isValid()" in file /home/appimage/workspace/Krita_Release_Appimage_Build/krita/libs/ui/KisDocument.cpp, line 504 Please report a bug to developers! Press Ignore to try to continue. Press Abort to see developers information (all unsaved data will be lost) Text from the terminal
(I can confirm using 4.2.0-pre-alpha (git 0ebf6d9) on Ubuntu 14.04)
This error still occurrs in 4.1.5, and also happens in Layer > Import/Export > Export Group Layers. Interestingly the Debian package hides the popup window and only prints the failed assertions in the console output, which is less annoying but also hides the problem.
Yes -- there are two ways to build Krita, one that shows the error in a message box, one that shows it on the command line. The latter is the default.
At the risk of my sanity I tirelessly delved into the arcane KisSharedPtr class. I believe I emerged with a fix for both cases: https://phabricator.kde.org/D17708
And that fix was pushed, too.