Fix typescript not generating ESM and add default values for rust types!

libjrpc/src/targets/rust.rs

@@ -463,7 +463,17 @@ impl Compile for RustCompiler {
 
         self.add_dependencies(&mut f, &definition.depends)?;
 
-        f.a0("#[derive(Clone, Debug, Serialize, Deserialize)]");
+        let only_optional = definition
+            .fields
+            .iter()
+            .find(|f| !f.typ.is_optional())
+            .is_none();
+
+        let derive_default_none = if only_optional { ", Default" } else { "" };
+        f.a0(format!(
+            "#[derive(Clone, Debug, Serialize, Deserialize{})]",
+            derive_default_none
+        ));
         f.a0(format!("pub struct {} {{", definition.name));
         for field in definition.fields.iter() {
             f.a(1, "#[allow(non_snake_case)]");