Minor: add an explicit na mapping to "<Missing>"

[Melkiades]

@shajoezhu this is the only change necessary for having continuity with the previous values

[github-actions]

Unit Tests Summary

  1 files  113 suites   3m 20s ⏱️
250 tests 219 ✅  31 💤 0 ❌
515 runs  267 ✅ 248 💤 0 ❌

Results for commit 4515ed0.

♻️ This comment has been updated with latest results.

[github-actions]

Unit Test Performance Difference

Test Suite	$Status$	Time on main	$±Time$	$±Tests$	$±Skipped$	$±Failures$	$±Errors$
pagination_table	💔	$10.87$	$+1.48$	$0$	$0$	$0$	$0$
table_aet03	💔	$1.61$	$+2.77$	$+4$	$0$	$0$	$0$
table_aet04	💔	$6.18$	$+5.33$	$+14$	$0$	$0$	$0$
table_lbt14	💚	$29.53$	$-1.61$	$0$	$0$	$0$	$0$
table_pkct01	💔	$1.66$	$+1.36$	$+5$	$0$	$0$	$0$

Additional test case details

Test Suite	$Status$	Time on main	$±Time$	Test Case
pagination_table	💔	$1.35$	$+1.69$	Pagination_works_for_page_types
table_aet03	💔	$1.61$	$+2.77$	AET03_variant_1_is_produced_correctly
table_pkct01	💔	$1.30$	$+1.19$	Specific_PKCT01_features_are_present

Results for commit 09a57b0

♻️ This comment has been updated with latest results.

[shajoezhu]

lgtm!