RCORE-2153: Fix issue when clearing a Lst<Mixed> in an upgraded file

[jedelbo]

What, How & Why?

Fixes #7771

☑️ ToDos

• 📝 Changelog update
• 🚦 Tests (or not relevant)
• C-API, if public C++ API changed
• bindgen/spec.yml, if public C++ API changed

[coveralls-official]

Pull Request Test Coverage Report for Build jorgen.edelbo_295

Details

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• 58 unchanged lines in 14 files lost coverage.
• Overall coverage decreased (-0.01%) to 90.95%

---

Files with Coverage Reduction	New Missed Lines	%
src/realm/dictionary.cpp	1	85.13%
test/test_util_network.cpp	1	95.56%
src/realm/query_expression.hpp	2	93.81%
test/test_lang_bind_helper.cpp	2	93.2%
src/realm/parser/driver.cpp	3	87.57%
src/realm/sync/client.cpp	3	91.78%
src/realm/sync/instruction_replication.cpp	3	91.48%
test/fuzz_group.cpp	3	48.8%
src/realm/link_translator.cpp	4	76.92%
src/realm/bplustree.cpp	6	72.55%

Totals
Change from base Build 2408:	-0.01%
Covered Lines:	214675
Relevant Lines:	236035

---

💛 - Coveralls

[ironage]

Fix seems fine. Please add a test, hopefully we have a list of mixed in one of the file upgrade tests you can use?

[jedelbo]

Unfortunately there is not any lists in the upgrade files. I will consider making a file with all our types so we can use that in future cases like this. But I will not do it in this context. I did verify, however, that we would hit this issue on an upgraded file.