fix(casting): dont crash on bad capdata

packages/agoric-cli/src/lib/wallet.js

@@ -112,6 +112,13 @@ export const coalesceWalletState = async (follower, invitationBrand) => {
   // values with oldest last
   const history = [];
   for await (const followerElement of iterateReverse(follower)) {
+    if ('error' in followerElement) {
+      console.error(
+        'Skipping wallet update due to error:',
+        followerElement.error,
+      );
+      continue;
+    }
     history.push(followerElement.value);
   }
 

packages/casting/src/follower-cosmjs.js

@@ -331,11 +331,16 @@ export const makeCosmjsFollower = (
     blockHeight,
     currentBlockHeight,
   ) => {
-    // AWAIT
-    const value = await /** @type {T} */ (
-      unserializer ? E(unserializer).fromCapData(data) : data
-    );
-    return { value, blockHeight, currentBlockHeight };
+    await null;
+    try {
+      // AWAIT
+      const value = await /** @type {T} */ (
+        unserializer ? E(unserializer).fromCapData(data) : data
+      );
+      return { value, blockHeight, currentBlockHeight };
+    } catch (e) {
+      return { blockHeight, currentBlockHeight, error: e, value: undefined };
+    }
   };
 
   /**

packages/casting/src/types.js

@@ -40,14 +40,17 @@ export {};
  */
 
 /**
- * @see {ChangeFollower}
- * @template T
- * @typedef {object} ValueFollowerElement
- * @property {T} value
+ * @typedef {object} ValueFollowerBase
  * @property {number} blockHeight
  * @property {number} currentBlockHeight
  */
 
+/**
+ * @see {ChangeFollower}
+ * @template T
+ * @typedef {ValueFollowerBase & ({ value: T } | { value: undefined, error: any })} ValueFollowerElement
+ */
+
 /**
  * @typedef {Pick<import('@endo/marshal').Marshal<unknown>, 'fromCapData' | 'unserialize'>} Unserializer
  */

packages/casting/test/test-mvp.js

@@ -1,5 +1,8 @@
 // @ts-nocheck
 // eslint-disable-next-line import/order
+import './lockdown.js';
+
+import { makeMarshal } from '@endo/marshal';
 import { test } from './prepare-test-env-ava.js';
 
 import {
@@ -167,6 +170,59 @@ test('unrecognized proof', async t => {
   );
 });
 
+test('yields error on bad capdata without terminating', async t => {
+  const marshal = makeMarshal();
+  const improperlyMarshalledData = { bad: 'data' };
+  const properlyMarshalledData = { foo: 'bar' };
+  const fakeValues = [
+    improperlyMarshalledData,
+    marshal.toCapData(harden(properlyMarshalledData)),
+  ];
+  t.plan(4);
+  const options = { batchSize: 1, marshaller: { toCapData: data => data } };
+  const { controller, PORT } = await t.context.startFakeServer(
+    t,
+    fakeValues,
+    options,
+  );
+  controller.advance(0);
+  /** @type {import('../src/types.js').LeaderOptions} */
+  const lo = {
+    retryCallback: null, // fail fast, no retries
+    keepPolling: () => delay(1000).then(() => true), // poll really quickly
+    jitter: null, // no jitter
+  };
+  /** @type {import('../src/types.js').FollowerOptions} */
+  const so = {
+    proof: 'none',
+  };
+
+  const leader = makeLeader(`http://localhost:${PORT}/network-config`, lo);
+  const castingSpec = makeCastingSpec(':mailbox.agoric1foobarbaz');
+  const follower = await makeFollower(castingSpec, leader, so);
+  let i = 0;
+  // eslint-disable-next-line no-unreachable-loop
+  for await (const { value, error } of iterateEach(follower)) {
+    if (i === 0) {
+      t.log(`value from follower, should be undefined:`, value);
+      t.log(`error from follower, should be defined:`, error);
+
+      t.deepEqual(value, undefined);
+      t.assert(typeof error === 'object');
+
+      i += 1;
+      controller.advance(1);
+    } else if (i === 1) {
+      t.log(`value from follower, should be defined:`, value);
+      t.log(`error from follower, should be undefined:`, error);
+
+      t.deepEqual(value, properlyMarshalledData);
+      t.deepEqual(error, undefined);
+      break;
+    }
+  }
+});
+
 test.before(t => {
   t.context.cleanups = [];
   t.context.startFakeServer = startFakeServer;