Fix a few simple sendability issues #118

Job	Run time
Unit tests / Construct unit test matrix	3s
Cxx interop / Construct Cxx interop matrix	2s
Soundness / API breakage check	4m 25s
Soundness / Documentation check	2m 54s
Soundness / Format check	34s
Soundness / Broken symlinks check	5s
Soundness / License headers check	5s
Soundness / Shell check	31s
Soundness / Unacceptable language check	5s
Soundness / YAML lint check	5s
Soundness / Python lint check	5s
Static SDK / Static SDK / Linux (latest-release Jammy)	3m 40s
Static SDK / Static SDK / Linux (main Jammy)	1m 56s
Cxx interop / Cxx interop / Linux (5.10)	2m 32s
Cxx interop / Cxx interop / Linux (6.0)	2m 57s
Cxx interop / Cxx interop / Linux (6.1)	2m 50s
Cxx interop / Cxx interop / Linux (nightly-next)	3m 31s
Cxx interop / Cxx interop / Linux (nightly-main)	3m 40s
Unit tests / Unit tests / Linux (5.10)	4m 41s
Unit tests / Unit tests / Linux (6.0)	5m 10s
Unit tests / Unit tests / Linux (6.1)	4m 59s
Unit tests / Unit tests / Linux (nightly-next)	5m 51s
Unit tests / Unit tests / Linux (nightly-main)	5m 54s
	56m 35s

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