chore(coprocessor): map verify_and_expand panics (if any) to an error

Author: goshawk-3

coprocessor/fhevm-engine/zkproof-worker/src/lib.rs

@@ -62,6 +62,9 @@ pub enum ExecutionError {
 
     #[error("Too many inputs: {0}")]
     TooManyInputs(usize),
+
+    #[error("Panic occurred during verify and expand: {0}")]
+    VerifyExpandPanic(String),
 }
 
 impl From<ExecutionError> for ServiceError {

coprocessor/fhevm-engine/zkproof-worker/src/verifier.rs

@@ -7,6 +7,7 @@ use fhevm_engine_common::tfhe_ops::{current_ciphertext_version, extract_ct_list}
 use fhevm_engine_common::types::SupportedFheCiphertexts;
 
 use fhevm_engine_common::utils::safe_deserialize_conformant;
+use fhevm_engine_common::with_panic_guard;
 use hex::encode;
 use lru::LruCache;
 use sha3::Digest;
@@ -353,7 +354,7 @@ pub(crate) fn verify_proof(
     set_server_key(keys.server_key.clone());
 
     let mut s = span.child_span("verify_and_expand");
-    let mut cts = match try_verify_and_expand_ciphertext_list(request_id, raw_ct, keys, aux_data) {
+    let mut cts = match verify_and_expand_with_guard(request_id, raw_ct, keys, aux_data) {
         Ok(cts) => {
             telemetry::attribute(&mut s, "count", cts.len().to_string());
             telemetry::end_span(s);
@@ -382,6 +383,24 @@ pub(crate) fn verify_proof(
     Ok((cts, blob_hash))
 }
 
+fn verify_and_expand_with_guard(
+    request_id: i64,
+    raw_ct: &[u8],
+    keys: &FetchTenantKeyResult,
+    aux_data: &auxiliary::ZkData,
+) -> Result<Vec<SupportedFheCiphertexts>, ExecutionError> {
+    with_panic_guard!(try_verify_and_expand_ciphertext_list(
+        request_id, raw_ct, keys, aux_data
+    ))
+    .map_err(|err| {
+        // Map panic to VerifyExpandPanic
+        ExecutionError::VerifyExpandPanic(format!(
+            "Panic occurred while verifying and expanding: {}",
+            err
+        ))
+    })?
+}
+
 fn try_verify_and_expand_ciphertext_list(
     request_id: i64,
     raw_ct: &[u8],