fix: error when saving changes to a v2 library block [FC-0059] #27366

Job	Run time
collect-and-verify	5m 8s
lms-1(py=3.11,dj=pinned,mongo=7.0)	10m 28s
lms-2(py=3.11,dj=pinned,mongo=7.0)	12m 55s
lms-3(py=3.11,dj=pinned,mongo=7.0)	14m 53s
lms-4(py=3.11,dj=pinned,mongo=7.0)	20m 53s
lms-5(py=3.11,dj=pinned,mongo=7.0)	11m 43s
lms-6(py=3.11,dj=pinned,mongo=7.0)	16m 26s
openedx-1-with-lms(py=3.11,dj=pinned,mongo=7.0)	11m 24s
openedx-2-with-lms(py=3.11,dj=pinned,mongo=7.0)	14m 40s
openedx-1-with-cms(py=3.11,dj=pinned,mongo=7.0)	7m 57s
openedx-2-with-cms(py=3.11,dj=pinned,mongo=7.0)	7m 5s
cms-1(py=3.11,dj=pinned,mongo=7.0)	5m 33s
cms-2(py=3.11,dj=pinned,mongo=7.0)	11m 54s
common-with-lms(py=3.11,dj=pinned,mongo=7.0)	9m 49s
common-with-cms(py=3.11,dj=pinned,mongo=7.0)	6m 14s
xmodule-with-lms(py=3.11,dj=pinned,mongo=7.0)	7m 14s
xmodule-with-cms(py=3.11,dj=pinned,mongo=7.0)	6m 52s
Unit tests successful	4s
compile-warnings-report	10s
coverage (3.11)	1m 38s
merge-artifacts	7s
	3h 3m 7s

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