Streamline error handling in `windows-bindgen` #122

Job	Run time
check (stable, x86_64-pc-windows-msvc, x86_64-pc-windows-msvc)	19m 57s
check (nightly, x86_64-pc-windows-msvc, i686-pc-windows-msvc)	20m 35s
check (nightly, x86_64-pc-windows-gnu, x86_64-pc-windows-gnu)	29m 44s
check (stable, x86_64-pc-windows-gnu, i686-pc-windows-gnu)	24m 52s
check (stable, x86_64-pc-windows-msvc, aarch64-pc-windows-msvc, --no-run)	21m 43s
check (nightly, x86_64-pc-windows-msvc, aarch64-pc-windows-msvc, --no-run)	18m 52s
	2h 15m 43s

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