test: add error equality tests + more warnings in docs #8490

Job	Run time
lint	1m 3s
test-browser-windows (chrome, chromium)	6m 45s
test-browser (chrome, chromium)	3m 21s
test-browser-windows (edge, webkit)	6m 27s
test (ubuntu-latest, 18)	10m 50s
test-browser (firefox, firefox)	3m 49s
test (ubuntu-latest, 20)	13m 3s
test-ui	1m 12s
test-browser (edge, webkit)	3m 14s
test (macos-14, 20)	8m 23s
test-ui-e2e (ubuntu-latest)	1m 52s
test (windows-latest, 20)	16m 10s
test-ui-e2e (macos-14)	4m 6s
typecheck	1m 54s
test-ui-e2e (windows-latest)	4m 11s
	1h 26m 20s

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