MM has a number of inconsistencies with other providers when implementing the JSON RPC interface. This subprovider wraps those nuances so they do not leak into the rest of our code
We use in-process ganache which throws on an RPC error. This means all of our tests get a nice revert error thrown when testing against ganache. This is not possible with RPC providers and a revert with reason result is returned. Our callAsync doesn't handle this and attempts to decode the revert with reason error log as a successful log, which results in an error while decoding.
This only works with our fork of ethers https://github.com/ethers-io/ethers.js/pull/188 and will need to be re-worked when updating to Ethers.js 4
