fix: make hosts non exhaustive

Author: prajwolrg

bin/prover-client/src/operators/operator.rs

@@ -96,6 +96,8 @@ impl ProofOperator {
 
             #[cfg(feature = "risc0")]
             ZkVmHostInstance::Risc0(host) => operator.prove(proof_key, db, host).await,
+
+            _ => unreachable!("Unexpected host variant"),
         }
     }
 

crates/zkvm/hosts/src/lib.rs

@@ -51,6 +51,7 @@ pub fn get_verification_key(key: &ProofKey) -> VerifyingKey {
 /// SP1, and Risc0, which each implement the [`ZkVmHost`](zkaleido::ZkVmHost) trait. The
 /// [`ZkVmHost`](zkaleido::ZkVmHost) trait is not object-safe, so this enum is used to encapsulate
 /// the different implementations.
+#[non_exhaustive]
 pub enum ZkVmHostInstance {
     /// Represents the native ZKVM host implementation.
     ///