fix(ERTP,vats): fix 9407 AmountPatternShape (#9863)

Staged on #9410 

closes: #9407 
refs: #9410 

## Description

Originally #9410 was supposed to fix #9407 , by relaxing an incorrect rejection into a correct acceptance. But we are not yet ready to deploy such a fix on-chain, due to upgrade constraints, so fixing it in agoric-sdk master would be misleading. It might lead people to write other code that depends on this bug being fixed when tested against agoric-sdk master, only to have that code fail later on-chain when invoking the non-upgraded buggy code.

So we unfixed #9410 to restore the buggy behavior, but with a better error message, and refactored to make fixing it again easier. This PR is that fix. It will remain draft until we are confident we can upgrade the relevant on-chain vat (the vbank) in a timely manner. Nevertheless, though we'll keep it in draft until then as a safety measure, this PR is reviewable. Reviewers, please review it.

### Security Considerations
Fixing a bug is generally good for security. Otherwise, none.

### Scaling Considerations
none

### Documentation Considerations
Would remove the need to document the #9407 buggy behavior

### Testing Considerations
Restores the `test.failing` from #9410 to a `test`.

### Upgrade Considerations
as above.

packages/vats/src/virtual-purse.js

@@ -1,7 +1,7 @@
 import { Fail } from '@endo/errors';
 import { E } from '@endo/far';
 import { isPromise } from '@endo/promise-kit';
-import { getInterfaceGuardPayload, matches } from '@endo/patterns';
+import { getInterfaceGuardPayload } from '@endo/patterns';
 
 import { M } from '@agoric/store';
 import {
@@ -105,22 +105,6 @@ export const makeVirtualPurseKitIKit = (
  *   current balance iterable for a given brand.
  */
 
-/**
- * Until https://github.com/Agoric/agoric-sdk/issues/9407 is fixed, this
- * function restricts the `optAmountShape`, if provided, to be a concrete
- * `Amount` rather than a `Pattern` as it is supposed to be.
- *
- * TODO: Once https://github.com/Agoric/agoric-sdk/issues/9407 is fixed, remove
- * this function and all calls to it.
- *
- * @param {Pattern} [optAmountShape]
- */
-const legacyRestrictAmountShapeArg = optAmountShape => {
-  if (optAmountShape && !matches(optAmountShape, AmountShape)) {
-    throw Fail`optAmountShape if provided, must still be a concrete Amount due to https://github.com/Agoric/agoric-sdk/issues/9407`;
-  }
-};
-
 /** @param {import('@agoric/zone').Zone} zone */
 const prepareVirtualPurseKit = zone =>
   zone.exoClassKit(
@@ -158,7 +142,6 @@ const prepareVirtualPurseKit = zone =>
          * @returns {Promise<Payment<'nat'>>}
          */
         async recoverableClaim(payment, optAmountShape) {
-          legacyRestrictAmountShapeArg(optAmountShape);
           const {
             state: { recoveryPurse },
           } = this;
@@ -186,7 +169,6 @@ const prepareVirtualPurseKit = zone =>
       minter: {
         /** @type {Retain} */
         async retain(payment, optAmountShape) {
-          legacyRestrictAmountShapeArg(optAmountShape);
           !!this.state.mint || Fail`minter cannot retain without a mint.`;
           return E(this.state.issuer).burn(payment, optAmountShape);
         },

packages/vats/test/vpurse.test.js

@@ -169,86 +169,6 @@ test('makeVirtualPurse', async t => {
     );
   };
 
-  expected.pushAmount(fungible837);
-  await E(vpurse)
-    .deposit(payment, fungible837)
-    .then(checkDeposit)
-    .then(performWithdrawal)
-    .then(checkWithdrawal);
-});
-
-// TODO Once https://github.com/Agoric/agoric-sdk/issues/9407 is fixed,
-// This test should replace the similar one above.
-test.failing('makeVirtualPurse with optAmountShape pattern', async t => {
-  t.plan(22);
-  const { baggage } = t.context;
-  const zone = makeDurableZone(baggage).subZone('makeVirtualPurse');
-
-  const { expected, balanceUpdater, issuer, mint, brand, vpurse } = setup(
-    t,
-    zone,
-  );
-
-  const payment = mint.mintPayment(AmountMath.make(brand, 837n));
-
-  const notifier = E(vpurse).getCurrentAmountNotifier();
-  let nextUpdateP = E(notifier).getUpdateSince();
-
-  const checkNotifier = async () => {
-    const { value: balance, updateCount } = await nextUpdateP;
-    t.assert(
-      AmountMath.isEqual(await E(vpurse).getCurrentAmount(), balance),
-      `the notifier balance is the same as the purse`,
-    );
-    nextUpdateP = E(notifier).getUpdateSince(updateCount);
-  };
-
-  balanceUpdater.updateState(AmountMath.makeEmpty(brand));
-  await checkNotifier();
-  t.assert(
-    AmountMath.isEqual(
-      await E(vpurse).getCurrentAmount(),
-      AmountMath.makeEmpty(brand),
-    ),
-    `empty purse is empty`,
-  );
-  t.is(await E(vpurse).getAllegedBrand(), brand, `purse's brand is correct`);
-  const fungible837 = AmountMath.make(brand, 837n);
-
-  const checkDeposit = async newPurseBalance => {
-    t.assert(
-      AmountMath.isEqual(newPurseBalance, fungible837),
-      `the amount returned is the payment amount`,
-    );
-    await checkNotifier();
-    t.assert(
-      AmountMath.isEqual(await E(vpurse).getCurrentAmount(), fungible837),
-      `the new purse balance is the payment's old balance`,
-    );
-  };
-
-  const performWithdrawal = () => {
-    expected.pullAmount(fungible837);
-    return E(vpurse).withdraw(fungible837);
-  };
-
-  const checkWithdrawal = async newPayment => {
-    await issuer.getAmountOf(newPayment).then(amount => {
-      t.assert(
-        AmountMath.isEqual(amount, fungible837),
-        `the withdrawn payment has the right balance`,
-      );
-    });
-    await checkNotifier();
-    t.assert(
-      AmountMath.isEqual(
-        await E(vpurse).getCurrentAmount(),
-        AmountMath.makeEmpty(brand),
-      ),
-      `the purse is empty again`,
-    );
-  };
-
   expected.pushAmount(fungible837);
   await E(vpurse)
     .deposit(payment, M.and(fungible837))