Removed defaultAccessList and fixed a couple of bugs

* draftAccessList is optional (and in some cases an error) with rev30
* Fixed credential expiration bug
* Fixed edge case where layer processing fails as already done
In this case, we only know how to handle one error, so if there's more than one error then it indicates that there's another unknown error that should go un-caught.

I noticed that I didn't re-throw the error in the != 1 case, so I've fixed that and added a comment to explain.