NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
STEPS TO REPRODUCE
1. copy an image from a photo or drawing that is open in krita
2. move to a new or different document in krita
3. use the "paste to cursor" selection
4. select ink tool "ink-2 fineliner"
5. draw lines
Krita fails to post the image and simply crashes, closing the entire program without saving or autosaving the document.
It took three attempts to actually get Krita to post as it is supposed to. The program crashed twice. The first crash I experienced was while trying to draw some lines, I was about 10 seconds into drawing some lines when it just crashed and closed on me, not saving the point I was at and forcing me to re-draw all the lines I had been doing within that time frame. In total there were three crashes without auto-saves to back up the point I was at before the crash itself, the crashes happened without warning and without any indication of what actually went wrong beyond using the tools I have listed in the step process.
I attempted to obtain a program to post the back trace here but couldn't find an actual download for the program that is stated in the website at the top, all it did was lead to a bunch of confusing links and no actual download.
I believe this bug should be fixed in the latest 5.1 nightlies. If it's not, feel free to ping us again.
*** This bug has been marked as a duplicate of bug 458941 ***