ValidatorAlreadySet
Author: Blockscape Finance AG info@blockscape.network
collects staking, mints NFT in return for staker and let's backend controller transfer the stake when the pool is full (currently 16 ETH) and enough RPL are available
this implementation relies on a backend controller which is a core component of the implementation.
error message if a validator is already set
error ValidatorAlreadySet(address _vali);