src/vs/workbench/services/history/browser/history.ts/HistoryService/safeLoadHistoryEntry
class HistoryService:	private safeLoadHistoryEntry(entry: ISerializedEditorHistoryEntry): IResourceEditorInput | undefined {
		const serializedEditorHistoryEntry = entry;

		// Untyped editor: take as is
		if (serializedEditorHistoryEntry.editor) {
			return serializedEditorHistoryEntry.editor;
		}

		// Legacy: old `resourceJSON` format
		if (serializedEditorHistoryEntry.resourceJSON) {
			return { resource: URI.revive(serializedEditorHistoryEntry.resourceJSON) };
		}

		return undefined;
	}