revise: better error messages

[claymcleod]

This PR adds better error messages through the use of thiserror and refining the language from some messages.

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• You have added tests (when appropriate).
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[github-actions]

Bencher Report

Branch	main
Testbed	github-actions

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• Latency (nanoseconds (ns))

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Benchmark	Latency	nanoseconds (ns)
contig::new	📈 view plot ⚠️ NO THRESHOLD	11.21 ns
coordinates::interbase::try_new	📈 view plot ⚠️ NO THRESHOLD	20.14 ns
intervals::interbase::try_new	📈 view plot ⚠️ NO THRESHOLD	53.81 ns
positions::base::checked_add	📈 view plot ⚠️ NO THRESHOLD	4.34 ns
positions::base::checked_sub	📈 view plot ⚠️ NO THRESHOLD	2.80 ns
positions::base::try_new	📈 view plot ⚠️ NO THRESHOLD	0.31 ns
positions::interbase::checked_add	📈 view plot ⚠️ NO THRESHOLD	1.87 ns
positions::interbase::checked_sub	📈 view plot ⚠️ NO THRESHOLD	0.62 ns
positions::interbase::new	📈 view plot ⚠️ NO THRESHOLD	0.31 ns

🐰 View full continuous benchmarking report in Bencher