GH-646 Add try-catch-log-and-drop on bls_signature creation to avoid …

…an exception killing the thread pool

libraries/chain/finality/finalizer.cpp

@@ -119,15 +119,17 @@ vote_message_ptr finalizer::maybe_vote(const bls_public_key& pub_key,
                                        const digest_type& digest) {
    finalizer::vote_decision decision = decide_vote(bsp).decision;
    if (decision == vote_decision::strong_vote || decision == vote_decision::weak_vote) {
-      bls_signature sig;
-      if (decision == vote_decision::weak_vote) {
-         // if voting weak, the digest to sign should be a hash of the concatenation of the finalizer_digest
-         // and the string "WEAK"
-         sig =  priv_key.sign(create_weak_digest(digest));
-      } else {
-         sig =  priv_key.sign({(uint8_t*)digest.data(), (uint8_t*)digest.data() + digest.data_size()});
-      }
-      return std::make_shared<vote_message>(bsp->id(), decision == vote_decision::strong_vote, pub_key, sig);
+      try {
+         bls_signature sig;
+         if (decision == vote_decision::weak_vote) {
+            // if voting weak, the digest to sign should be a hash of the concatenation of the finalizer_digest
+            // and the string "WEAK"
+            sig =  priv_key.sign(create_weak_digest(digest));
+         } else {
+            sig =  priv_key.sign({(uint8_t*)digest.data(), (uint8_t*)digest.data() + digest.data_size()});
+         }
+         return std::make_shared<vote_message>(bsp->id(), decision == vote_decision::strong_vote, pub_key, sig);
+      } FC_LOG_AND_DROP() // bls_signature can throw if invalid signature
    }
    return {};
 }