These are two different issues, coming from the same commit.
I. Perform the steps of bug 139135.
1. Open attachment 155631 [details] from bug 104254,
II. Insert a section using Insert -> Section..., then press Insert.
Regressions are from the following commit.
author Noel Grandin <email@example.com> 2021-08-28 08:35:29 +0200
committer Noel Grandin <firstname.lastname@example.org> 2021-08-28 15:13:20 +0200
speedup dynamic_cast to SwTextFrame
Proposed fix: https://gerrit.libreoffice.org/c/core/+/121662
Aron Budea committed a patch related to this issue.
It has been pushed to "master":
tdf#144304 Fix crashes from "speedup dynamic_cast to SwTextFrame"
It will be available in 7.3.0.
The patch should be included in the daily builds available at
https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.
*** Bug 144321 has been marked as a duplicate of this bug. ***