Preserve NULL semantics for incremental SUM #490

Job	Run time
Code Quality Check / Format Check	3m 9s
Code Quality Check / Tidy Check	37m 13s
Build extension binaries / Generate matrix	5s
Build extension binaries / Linux (linux_amd64, ubuntu-24.04, x64-linux-release, x64-linux-release, true, false)	14m 22s
Build extension binaries / Linux (linux_arm64, ubuntu-24.04-arm, arm64-linux-release, arm64-linux-release, false, false)	8m 52s
Build extension binaries / MacOS (osx_arm64, arm64, arm64-osx-release, arm64-osx-release, true, false)	11m 38s
Build extension binaries / DuckDB-Wasm (wasm_eh, wasm32-emscripten, x64-linux, false, false)	10m 18s
Build extension binaries / DuckDB-Wasm (wasm_mvp, wasm32-emscripten, x64-linux, true, false)	9m 11s
Build extension binaries / Windows (windows_amd64, windows-latest, x64-windows-static-release, x64-windows-static-release, t...	14m 57s
Build extension binaries / Windows (windows_amd64_mingw, windows-latest, x64-mingw-static, x64-mingw-static, true, false)	20m 24s
Build extension binaries / DuckDB-Wasm (wasm_threads, wasm32-emscripten, x64-linux, false, false)	13m 34s
Build extension binaries / MacOS (osx_amd64, x86_64, x64-osx-release, arm64-osx-release, false, false)	7m 26s
	2h 31m 9s

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