evo: Fix CEvoDB::VerifyBestBlock (#4040)
evo: Fix CEvoDB::VerifyBestBlock (#4040)

Just return the result of the comparison in case there is a block and
false otherwise. This should allow to reach the currently unreachable
two error cases below instead of crashing because the assert doesn't
pass in case of inconsistency.
https://github.com/dashpay/dash/blob/c2d7d0cab4f83692db5a6003ae387c4f821fcabd/src/validation.cpp#L1687-L1691
https://github.com/dashpay/dash/blob/c2d7d0cab4f83692db5a6003ae387c4f821fcabd/src/validation.cpp#L2094-L2098
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin