macos

Fix SEGV on null StringIO #476

Job	Run time
ruby-versions / Generate Ruby versions	5s
macos-13 3.0	25s
macos-13 3.2	24s
macos-13 2.7	52s
macos-13 3.1	18s
macos-14 3.2	15s
macos-14 3.1	15s
macos-14 2.7	32s
macos-13 3.4	35s
macos-14 3.0	15s
macos-13 debug	29s
macos-13 head	23s
macos-14 3.4	15s
macos-14 debug	18s
macos-13 3.3	24s
macos-14 3.3	13s
macos-14 head	18s
	6m 16s

Provide feedback