Added a minimum for network difficulty at one

src/consensus/pob/vdf.rs

@@ -19,6 +19,7 @@ const MAXIMUM_ITERATIONS: u64 = 800_000_000; //approximately one day
 /// Compute the delay parameter in seconds of a VDF to run
 pub fn compute_vdf_difficulty(network_difficulty: u64, hash: H256, quantity: U256) -> u64 {
     let vdf_difficulty = U256::from(network_difficulty)
+        .max(U256::ONE)
         .wrapping_mul(h256_to_u256(hash))
         .as_u64()
         % MAXIMUM_ITERATIONS