jspg error refactoring checkpoint

src/drop.rs

@@ -57,10 +57,13 @@ impl Drop {
   }
 }
 
+use std::collections::HashMap;
+
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub struct Error {
   pub code: String,
-  pub message: String,
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub values: Option<HashMap<String, String>>,
   pub details: ErrorDetails,
 }