Errors from ecSignOrderAsync not being handled

[albrow]

I had a bug in my code that caused signatureUtils.ecSignOrderAsync to reject/throw here. It was difficult to track down what was going on because AFAICT the error is just being swallowed up without being logged.

There might be an easier way to reproduce this, but here's more or less what I did:

1. Modify getOrderWithTakerAndFeeConfigFromRelayer to include an invalid field. I had accidentally set makerFeeAssetData to 0x0 instead of 0x.
2. Open launch kit front end in your browser and try to create an order. The MetaMask pop up never shows up and it just says it failed.