Comment 7 for bug 1605003

yes, you should never tyr to launch the wrapper script directly, there is another wrapper around that that prepares the environment ... the two mkdirs most likely try to create $SNAP_USER_DATA/{.local,.cache} ... but SNAP_USER_DATA gets only set by the outer launcher ...

you should actually have gotten /snap/bin/krita along with the snap and the snapd package should have exported /snap/bin into your PATH ... so either just calling "krita" or (if the PATH entry is yet missing) /snap/bin/krita should get you a running app.