race condition in smartWallet addBrand handling

[turadg]

Describe the bug

In some versions of XS, the non-init updateBalance hits before the init one, causing an assert to fail when checking for the presence of the key in the collection.

In general while the purse is guaranteed to see the messages getCurrentAmount and getCurrentAmountNotifier in order, there is no guarantee those will be resolved in the same order. And even if they were, E.when and the observeNotifier may not make any guarantee about the number of turns or cranks that may occur.

agoric-sdk/packages/smart-wallet/src/smartWallet.js

Lines 320 to 334 in c7d4223

	// publish purse's balance and changes
	E.when(
	E(purse).getCurrentAmount(),
	balance => helper.updateBalance(purse, balance, 'init'),
	err =>
	console.error(address, 'initial purse balance publish failed', err),
	);
	observeNotifier(E(purse).getCurrentAmountNotifier(), {
	updateState(balance) {
	helper.updateBalance(purse, balance);
	},
	fail(reason) {
	console.error(address, `failed updateState observer`, reason);
	},
	});

To Reproduce

Not practical to reproduce. Just fix through code analysis.

Expected behavior

No assertion failure if promises resolve in another valid resolution order.

Platform Environment

XS

Additional context

#6689 (comment)

Screenshots

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