smart wallet fails on 2nd payment from unknown brand

[dckc]

Describe the bug

Payments bearing unknown brands are supposed to be queued until the corresponding issuer is added. In the queue implementation, an array is hardened and then we later .push() to it, which throws.

To Reproduce

Run this test:

agoric-sdk/packages/inter-protocol/test/smartWallet/test-psm-integration.js

Line 363 in b63db15

test.failing('deposit > 1 payment to unknown brand', async t => {

Expected behavior

doesn't throw. Payment is deposited when the issuer comes along

Additional context

Unknown brands are only possible in MN-2 / MN-3 / devnet.

cc @turadg