Download the attached broken.xps to /tmp and run in zsh:
org.kde.okular.generators.xps: Successful open of "/tmp/broken.xps"
org.kde.okular.generators.xps: document file name: "/Documents/1/FixedDocument.fdoc"
org.kde.okular.generators.xps: Page Path: "Pages/1.fpage"
org.kde.okular.generators.xps: generating document synopsis
zsh: segmentation fault okular broken.xps
{}> echo $?
139
I expect a meaningful and specific error message on what is wrong inside the file instead of a segfault.