Oh turns out we can return &str after all.

Author: JDSeiler

src/error.rs

@@ -100,8 +100,8 @@ impl StructuredError {
   /// reporting mechanism. Instead of calling this method, you can access the 
   /// StructuredError `message` field directly.
   #[deprecated(since="0.3.3", note="Please use the `message` field directly instead.")]
-  pub fn message(&self) -> &String {
-    self.message.as_ref().unwrap()
+  pub fn message(&self) -> &str {
+    self.message.as_ref().unwrap().as_str()
   }
 
   /// Returns the provided c_str as Some(String), or None if the provided pointer is null.