Autoswap returns results as strings; clients compare strings to learn outcome

[Chris-Hibbert]

This is a request for discussion, not a particular proposal for a solution.

What is the Problem Being Solved?

Autoswap (and other contracts) return success and failure indication as strings. Clients must compare strings to learn the outcome. For many contracts the outcome is almost always a success, since either give or want satisfies offer safety. With Autoswap, the distinction between /Swap successfully completed/ and / is insufficient to buy amountOut / tells whether the trade went through.

Description of the Design

Doing a string compare on the results seems infelicitous. Maybe the contracts could publish some enum values? I don't think we have enough common outcomes across contracts to standardize this yet, so it would have to be for each contract.

Security Considerations

This is mostly about usability, I think.

Test Plan

As we figure out what we want

[katelynsills]

We need to improve the code in Multipool Autoswap, as this isn't generally how contracts work. They generally work much better - getOfferResult throws and it is the promise rejection that indicates an error. See #2336 for the issue detailing what needs to be done.