priceQuery must return a quote

[katelynsills]

Describe the bug

2021-04-07T01:24:16.904Z SwingSet: vat: v16: ----- VV.7  2 vaultSeat proposal { want: {}, give: {}, exit: { onDemand: null } }
UnhandledPromiseRejectionWarning: (Error#38)
Error#38: priceQuery must return a quote

  at createQuote (packages/zoe/src/contracts/multipoolAutoswap/priceAuthority.js:42:20)
  at mutableTrigger (packages/zoe/src/contractSupport/priceAuthority.js:169:40)
  at Alleged: PriceAuthority.mutableQuoteWhenOutTrigger [as mutableQuoteWhenLT] (packages/zoe/src/contractSupport/priceAuthority.js:202:25)

Error#38 ERROR_NOTE: Rejection from: (Error#39) : 5478 . 0
Nested error under Error#38
  Error#39: Event: 5477.1
  
    at Function.applyMethod (packages/tame-metering/src/tame.js:184:20)
    at meteredConstructor.deliver (packages/SwingSet/src/kernel/liveSlots.js:525:28)
    at eval (packages/SwingSet/src/kernel/vatManager/deliver.js:51:48)
  
Error#38 ERROR_NOTE: Sent as error:liveSlots:v17#70005
2021-04-07T01:24:17.146Z SwingSet: ls: v17: Logging sent error stack (Error#38)
(node:38522) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 3)
UnhandledPromiseRejectionWarning: (RemoteError(error:liveSlots:v17#70005)#40)
RemoteError(error:liveSlots:v17#70005)#40: priceQuery must return a quote

  at fullRevive (packages/marshal/src/marshal.js:874:43)
  at meteredConstructor.unserialize (packages/marshal/src/marshal.js:954:19)
  at notifyOnePromise (packages/SwingSet/src/kernel/liveSlots.js:597:19)
  at meteredConstructor.notify (packages/SwingSet/src/kernel/liveSlots.js:610:7)
  at eval (packages/SwingSet/src/kernel/vatManager/deliver.js:51:48)

RemoteError(error:liveSlots:v17#70005)#40 ERROR_NOTE: Rejection from: (Error#41) : 5476 . 0
Nested error under RemoteError(error:liveSlots:v17#70005)#40
  Error#41: Event: 5475.1
  
    at Function.applyMethod (packages/tame-metering/src/tame.js:202:19)
    at Proxy.eval (packages/eventual-send/src/E.js:37:126)
    at reschedulePriceCheck (packages/treasury/src/vaultManager.js:123:60)
  

To Reproduce

Occurs when creating a vault and then closing it immediately afterward. Trying to find the minimal steps to reproduce.

[erights]

This looks like a good actual example of a cross vat bug that can be tracked back to its origin using the extra tracking info added by ses 0.12.7. Did this turn out to be useful in practice? Is this sufficiently representative of other bugs we expect people to run into that it is a good expository example?

[Chris-Hibbert]

Did this turn out to be useful in practice?

The top of the stack and the error message showed me all the context I needed. I re-studied the model I had based the code on (priceAggregator) and figured out why the assertion was incorrect. #2839 is the fix.

I think that means the answer to your question is mostly yes, but I didn't actually need the context, etiology or symptoms to figure out what was wrong.