Merge branch 'develop' into claude/basic-json-template-assumptions-tyc76m

Picks up the fix for the unconditional array reserve() (#5522), which
made the new custom-array-type test fail to compile on AppVeyor.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

include/nlohmann/json.hpp

@@ -3633,6 +3633,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         std::swap(m_data.m_type, other.m_data.m_type);
         std::swap(m_data.m_value, other.m_data.m_value);
 
+#if JSON_DIAGNOSTIC_POSITIONS
+        std::swap(start_position, other.start_position);
+        std::swap(end_position, other.end_position);
+#endif
+
         set_parents();
         other.set_parents();
         assert_invariant();