Fix BSP.split_recursive crash when passing Random #1305

Job	Run time
sdist	3m 11s
ruff	6s
mypy	24s
parse_sdl (macos-latest, 3.2.16)	25s
parse_sdl (windows-latest, 3.2.16)	44s
test-docs	3m 58s
build (windows-latest, 3.10, x86)	3m 31s
build (ubuntu-latest, 3.10, x64)	7m 1s
linux-wheels (aarch64, cp310-manylinux*)	3m 53s
tox (ubuntu-latest)	4m 34s
build (windows-latest, 3.10, x64)	4m 5s
linux-wheels (x86_64, pp310-manylinux*)	3m 50s
build (ubuntu-latest, pypy-3.10, x64)	6m 18s
linux-wheels (x86_64, cp310-manylinux*)	4m 6s
build-macos (pp310-*)	4m 55s
linux-wheels (aarch64, pp310-manylinux*)	3m 46s
pyodide	3m 53s
build (windows-latest, pypy-3.10, x64)	4m 28s
build-macos (cp310-*_universal2)	1m 51s
publish	0s
	1h 4m 59s

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