Define `Warning` type and start annotating possible parse errors #402

Job	Run time
Clippy	10s
Test performance on benchmarks	2m 26s
License / vulnerability audit (advisories)	20s
License / vulnerability audit (bans licenses sources)	21s
Enforce Rust code format	15s
Preflight docs.rs build	14s
Preflight crate publish (ubuntu-latest, stable)	11s
Unit tests with minimum versions of direct dependencies (windows-latest)	59s
Unit tests (windows-latest, stable)	1m 9s
Unit tests with minimum versions of direct dependencies (macos-latest)	26s
Check for unused dependencies	23s
Unit tests (windows-latest, 1.74.0)	52s
Unit tests with minimum versions of direct dependencies (ubuntu-latest)	34s
Unit tests (macos-latest, stable)	36s
Unit tests (macos-latest, 1.74.0)	39s
Unit tests (ubuntu-latest, stable)	25s
Unit tests (ubuntu-latest, 1.74.0)	31s
	10m 31s

Provide feedback