add panic message when trying to derive TypeUuid on a generic

crates/bevy_reflect/bevy_reflect_derive/src/type_uuid.rs

@@ -1,6 +1,6 @@
 extern crate proc_macro;
 
-use quote::quote;
+use quote::{quote, ToTokens};
 use syn::{parse::*, *};
 use uuid::Uuid;
 
@@ -15,7 +15,11 @@ pub fn type_uuid_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStre
 
     // Build the trait implementation
     let name = &ast.ident;
-    let (_impl_generics, _type_generics, _where_clause) = &ast.generics.split_for_impl();
+    let (impl_generics, type_generics, _) = &ast.generics.split_for_impl();
+
+    if !impl_generics.to_token_stream().is_empty() || !type_generics.to_token_stream().is_empty() {
+        panic!("#[derive(TypeUuid)] is not supported for generics.");
+    }
 
     // TODO: panic if there are generics.