Make aggregator prover fail when trying to add key to the merkle tree

Before it allowed to add new keys to the merkle tree, making it create
proofs based on a different merkle root than the one signed in the last
certificate.

Even more worrisome this merkle tree would be then returned modified
to its mkpool, making this corruption persist until the pool is refreshed.

Author: Alenar

mithril-aggregator/src/services/prover.rs

@@ -141,7 +141,7 @@ impl ProverService for MithrilProverService {
 
         // 4 - Enrich the Merkle map with the block ranges Merkle trees
         for (block_range, mk_tree) in mk_trees {
-            mk_map.insert(block_range, mk_tree.into())?;
+            mk_map.replace(block_range, mk_tree.into())?;
         }
 
         // 5 - Compute the proof for all transactions
@@ -167,7 +167,8 @@ impl ProverService for MithrilProverService {
         let pool_size = self.mk_map_pool.size();
         info!(
             self.logger,
-            "Prover starts computing the Merkle map pool resource of size {pool_size}"
+            "Prover starts computing the Merkle map pool resource of size {pool_size}";
+            "up_to_block_number" => up_to,
         );
         let mk_map_cache = self
             .block_range_root_retriever