Fix error swallowing by propagating JSON serialization errors to LLM

server/src/handlers/env.rs

@@ -62,7 +62,7 @@ impl McpTool for ReadEnvFingerprintHandler {
             .read_with(|fps| fps.get(&req.namespace).cloned());
         if let Some(fp) = data {
             let data = serde_json::to_string(&fp).unwrap_or_default();
-            Ok(data.to_string())
+            Ok(data)
         } else {
             Ok("{}".to_string())
         }
@@ -155,9 +155,9 @@ impl McpTool for GetEnvironmentDetailsHandler {
                 .iter()
                 .filter(|e| e.namespace == req.namespace)
                 .collect();
-            serde_json::to_string(&filtered).unwrap_or_default()
-        });
-        Ok(data.to_string())
+            serde_json::to_string(&filtered).map_err(|e| e.to_string())
+        })?;
+        Ok(data)
     }
 }