Define `Warning` type and start annotating possible parse errors #403

Job	Run time
License / vulnerability audit (advisories)	25s
Enforce Rust code format	21s
Test performance on benchmarks	31s
License / vulnerability audit (bans licenses sources)	17s
Clippy	21s
Preflight docs.rs build	14s
Preflight crate publish (ubuntu-latest, stable)	11s
Unit tests with minimum versions of direct dependencies (windows-latest)	44s
Unit tests (windows-latest, stable)	2m 2s
Unit tests with minimum versions of direct dependencies (macos-latest)	26s
Unit tests (windows-latest, 1.74.0)	1m 1s
Unit tests with minimum versions of direct dependencies (ubuntu-latest)	24s
Check for unused dependencies	26s
Unit tests (macos-latest, stable)	28s
Unit tests (macos-latest, 1.74.0)	42s
Unit tests (ubuntu-latest, stable)	29s
Unit tests (ubuntu-latest, 1.74.0)	30s
	9m 32s

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