Fix optional bodies #3137

Job	Run time
test_min_deps (windows-latest)	1m 9s
test_min_deps (macos-latest)	52s
test_min_deps (ubuntu-latest)	45s
Integration Tests (pdm.minimal.lock)	22s
Integration Tests (pdm.lock)	30s
test (3.11, macos-latest)	52s
test (3.11, windows-latest)	2m 4s
test (3.11, ubuntu-latest)	1m 10s
test (3.10, ubuntu-latest)	1m 2s
test (3.10, macos-latest)	1m 15s
test (3.12, windows-latest)	1m 50s
test (3.12, macos-latest)	1m 1s
test (3.10, windows-latest)	1m 47s
test (3.12, ubuntu-latest)	1m 8s
test (3.13, ubuntu-latest)	1m 18s
test (3.14, ubuntu-latest)	1m 6s
test (3.13, windows-latest)	1m 56s
test (3.14, windows-latest)	1m 54s
test (3.14, macos-latest)	43s
test (3.13, macos-latest)	56s
Combine & check coverage	14s
	23m 54s

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