chore: improve error span

crates/relax-macros/src/lib.rs

@@ -19,13 +19,13 @@ fn derive_impl(input: syn::DeriveInput) -> syn::Result<TokenStream> {
 
     if relax_attrs.is_empty() {
         return Err(syn::Error::new_spanned(
-            input,
+            input.ident,
             "expected #[relax(StructName)] attrubute",
         ));
     }
     if relax_attrs.len() > 1 {
         return Err(syn::Error::new_spanned(
-            input,
+            input.ident,
             "expected only one #[relax(StructName)] attrubute on top of the struct",
         ));
     }