Reused CoinsViewOverlay layered on top of m_cacheview and passed to ConnectBlock(). Reset between calls and flushed only on success, so invalid blocks don't pollute the underlying cache.
Declared in <validation.h>
[[guarded_by(0x7f95139b7328), guarded_by(0x7f9501ef63a8), guarded_by(0x7f952537d178), guarded_by(0x7f95150ff6c8)]]
std::unique_ptr<CoinsViewOverlay> m_connect_block_view;