Add derive Debug for error enums

Author: noise64

src/rust/client_gen.rs

@@ -674,6 +674,7 @@ fn render_errors(method_name: &str, error_kind: &ErrorKind, errors: &MethodError
 
     #[rustfmt::skip]
     let res = unit() +
+        line(unit() + "#[derive(Debug)]") +
         line(unit() + "pub enum " + name + " {") +
         indented(
             code_cases

src/rust/error_gen.rs

@@ -19,6 +19,7 @@ pub fn error_gen() -> Module {
     let code = indoc! { r#"
         use bytes::Bytes;
 
+        #[derive(Debug)]
         pub enum Error<T> {
             Item(T),
             Reqwest(reqwest::Error),