Removed return statement as they prevent an exception from being thrown
Removed return statement as they prevent an exception from being thrown

If the reason doesn't match in `handleInvalidApiUsage`, no exceotion is
ever thrown. Removing the return statement will let it fall through to
`throw $ex` in `handleBadResponseException`

Sneek/gocardless-pro,fyfey/gocardless-pro,stephangroen/gocardless-pro