revert out-of-scope register_validator body-prep change

Author: JasonVranek

crates/pbs/src/mev_boost/register_validator.rs

@@ -35,19 +35,17 @@ pub async fn register_validator<S: BuilderApiState>(
         .insert(HEADER_START_TIME_UNIX_MS, HeaderValue::from_str(&utcnow_ms().to_string())?);
     send_headers.insert(USER_AGENT, get_user_agent_with_version(&req_headers)?);
 
-    // prepare the body in advance
-    let bodies: Vec<(usize, Bytes)> =
+    // prepare the body in advance, ugly dyn
+    let bodies: Box<dyn Iterator<Item = (usize, Bytes)>> =
         if let Some(batch_size) = state.config.pbs_config.validator_registration_batch_size {
-            registrations
-                .chunks(batch_size)
-                .map(|batch| {
-                    let body = serde_json::to_vec(batch).map_err(PbsError::JsonEncode)?;
-                    Ok((batch.len(), Bytes::from(body)))
-                })
-                .collect::<Result<Vec<_>, PbsError>>()?
+            Box::new(registrations.chunks(batch_size).map(|batch| {
+                // SAFETY: unwrap is ok because we're serializing a &[serde_json::Value]
+                let body = serde_json::to_vec(batch).unwrap();
+                (batch.len(), Bytes::from(body))
+            }))
         } else {
-            let body = serde_json::to_vec(&registrations).map_err(PbsError::JsonEncode)?;
-            vec![(registrations.len(), Bytes::from(body))]
+            let body = serde_json::to_vec(&registrations).unwrap();
+            Box::new(std::iter::once((registrations.len(), Bytes::from(body))))
         };
     send_headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));