UI: bad offers fail silently

[dckc]

In #20 , the user can give less than the joinPrice or want more than 3 places. The contract correctly rejects such offers, but the UI does not show the error.

In the console, I see:

ses.js?v=331fbee1:3670 SES_UNHANDLED_REJECTION: Error: Passed Error "stack" {"configurable":false,"enumerable":false,"get":"[Function <anon>]","set":"[Function <anon>]"} must be a string-valued data property.
  at Array.map (<anonymous>)
  at Array.map (<anonymous>)
  at Array.map (<anonymous>)
  at Array.map (<anonymous>)
handleRejection	@	ses.js?v=331fbee1:3670
finalizeDroppedPromise	@	ses.js?v=331fbee1:3594
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@samsiegart you dealt with this in some of our dapps already, yes?
I should be able to find that issue and its fix on my own...

cc @0xpatrickdev

[samsiegart]

This issue is the same as Agoric/ui-kit#57. It's fixed in the latest release of ui-kit, but it requires updating @agoric/rpc and @agoric/web-components which involves breaking changes. For reference, these are the updates made to dapp-inter to use those new versions