Update rng function
Update rng function

In case someone copy pastes, instead of getting a dangerous key, they will get a random key, and a console error.
visvirial/bitcoinjs-lib,visvirial/bitcoinjs-lib,BitGo/bitcoinjs-lib,BitGo/bitcoinjs-lib,bitcoinjs/bitcoinjs-lib,junderw/bitcoinjs-lib,bitcoinjs/bitcoinjs-lib,junderw/bitcoinjs-lib