New test for another error case in DepositScriptAddress

Is this really the best way to do this? It uses a callback in order to actually run the test, which isn't easy to see.
Something like Get/SetCryptoKeyScript in internal_test which gets/sets the mgr.cryptoKeyScript should be enough without all this callback business. This way the DepositScriptAddress function can be called cleanly after the set and error checked afterwards.