Add error info in validator

Author: zjb0807

Diff for: rust/main/agents/validator/src/validator.rs

@@ -200,8 +200,9 @@ impl BaseAgent for Validator {
                     }
                     break;
                 }
-                _ => {
+                Err(err)  => {
                     // Future that immediately resolves
+                    error!(?err, "Failed to get the merkle tree hook count");
                     return;
                 }
             }