Implement Display for the error enum

src/lib.rs

@@ -335,11 +335,19 @@ fn derive_protocol(input: proc_macro2::TokenStream) -> proc_macro2::TokenStream
 
     // Create an error and result type for sending messages
     let error_enum = quote! {
-        #[derive(Debug)]
+        #[derive(::std::fmt::Debug)]
         #vis enum #error_enum_name {
             SendError(::tokio::sync::mpsc::error::SendError<(u64, #question_enum_name)>),
             Closed,
         }
+        impl ::std::fmt::Display for #error_enum_name {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
+                match self {
+                    #error_enum_name::SendError(e) => write!(f, "Failed to send query: {}", e),
+                    #error_enum_name::Closed => write!(f, "Connection closed"),
+                }
+            }
+        }
     };
     // Create enums for the types of messages the server and client will use