Remove old debugging code, fix API fault

eth2/proto_array_fork_choice/Cargo.toml

@@ -17,4 +17,3 @@ eth2_ssz_derive = "0.1.0"
 serde = "1.0.102"
 serde_derive = "1.0.102"
 serde_yaml = "0.8.11"
-serde_json = "1.0"

eth2/proto_array_fork_choice/src/proto_array.rs

@@ -18,7 +18,7 @@ pub struct ProtoNode {
     best_descendant: Option<usize>,
 }
 
-#[derive(PartialEq, Serialize, Deserialize)]
+#[derive(PartialEq, Debug, Serialize, Deserialize)]
 pub struct ProtoArray {
     /// Do not attempt to prune the tree unless it has at least this many nodes. Small prunes
     /// simply waste time.

eth2/proto_array_fork_choice/src/proto_array_fork_choice.rs

@@ -1,8 +1,7 @@
 use crate::error::Error;
 use crate::proto_array::ProtoArray;
 use crate::ssz_container::SszContainer;
-use parking_lot::RwLock;
-use serde_json;
+use parking_lot::{RwLock, RwLockReadGuard};
 use ssz::{Decode, Encode};
 use ssz_derive::{Decode, Encode};
 use std::collections::HashMap;
@@ -213,9 +212,11 @@ impl ProtoArrayForkChoice {
             .map_err(|e| format!("Failed to decode ProtoArrayForkChoice: {:?}", e))
     }
 
-    pub fn as_json(&self) -> Result<String, String> {
-        serde_json::to_string(&*self.proto_array.read())
-            .map_err(|e| format!("Failed to JSON encode proto_array: {:?}", e))
+    /// Returns a read-lock to core `ProtoArray` struct.
+    ///
+    /// Should only be used when encoding/decoding during troubleshooting.
+    pub fn core_proto_array(&self) -> RwLockReadGuard<ProtoArray> {
+        self.proto_array.read()
     }
 }