Make scheduler thread errors a little better #1134

Job	Run time
Tests / cargo-deny	34s
Tests / cargo-clippy	35s
Tests / inko-fmt	51s
Tests / cargo-fmt	19s
Tests / Linux AMD64	1m 29s
Tests / macOS AMD64	2m 33s
Tests / vale	20s
Tests / macOS ARM64	1m 58s
Tests / FreeBSD AMD64	3m 42s
Standard library documentation	1m 40s
Nightly container	2m 15s
Documentation	33s
	16m 49s

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