This fixes a crash on the google photos backend when an error is
returned from the rest.Call function.
This turned out to be a mis-understanding of the rest docs so
- improved rest.Call docs
- fixed mis-understanding in google photos backend
- fixed similar mis-understading in onedrive backend
This was factored from fstest as we were including the testing
enviroment into the main binary because of it.
This was causing opening the browser to fail because of 8243ff8bc8.