add todo comment with issue

barretenberg/cpp/src/barretenberg/client_ivc/client_ivc.cpp

@@ -77,6 +77,9 @@ HonkProof ClientIVC::decider_prove() const
  * recursive merge verifier), initial kernel verification key (with recursive merge verifier appended, no previous
  * kernel to fold), "full" kernel verification key( two recursive folding verifiers and merge verifier).
  *
+ * TODO(https://github.com/AztecProtocol/barretenberg/issues/904): This function should ultimately be moved outside of
+ * this class since it's used only for testing and benchmarking purposes and it requires us to clear state afterwards.
+ * (e.g. in the Goblin object)
  */
 void ClientIVC::precompute_folding_verification_keys()
 {

barretenberg/cpp/src/barretenberg/goblin/goblin.hpp

@@ -89,7 +89,12 @@ class Goblin {
     AccumulationOutput accumulator; // Used only for ACIR methods for now
 
   public:
-    Goblin() { GoblinMockCircuits::perform_op_queue_interactions_for_mock_first_circuit(op_queue); }
+    Goblin()
+    { // Mocks the interaction of a first circuit with the op queue due to the inability to currently handle zero
+      // commitments (https://github.com/AztecProtocol/barretenberg/issues/871) which would otherwise appear in the
+      // first round of the merge protocol. To be removed once the issue has been resolved.
+        GoblinMockCircuits::perform_op_queue_interactions_for_mock_first_circuit(op_queue);
+    }
     /**
      * @brief Construct a GUH proof and a merge proof for the present circuit.
      * @details If there is a previous merge proof, recursively verify it.