workspace: streamline error types for load() functions #977

Job	Run time
build (stable) / rust	33s
build (nightly) / rust	19s
build (msrv) / rust	50s
tests with miri (nightly)	0s
build no_std (nightly)	0s
style (nightly)	0s
build no_std (stable) [w/o builder] / rust	12s
build no_std (stable) [Windows] / rust	2m 0s
build no_std (stable) / rust	16s
style (stable) / rust	29s
style (msrv) / rust	21s
build no_std (msrv) / rust	20s
	5m 20s

Provide feedback