Fix infinite loop when diffing non-equatable recursive objects #492

Job	Run time
Android (Swift 6.0.2)	7m 26s
Ubuntu (5.10)	54s
Wasm	59s
macOS 14 (Xcode 15.4)	5m 45s
Windows (windows-latest, debug)	1m 49s
Windows (windows-latest, release)	1m 58s
	18m 51s

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