fix: handle empty type_args in define-trait definition

Author: hugoclrd

clarity/src/vm/types/signatures.rs

@@ -1655,6 +1655,9 @@ impl TypeSignature {
         epoch: StacksEpochId,
         clarity_version: ClarityVersion,
     ) -> Result<BTreeMap<ClarityName, FunctionSignature>> {
+        if type_args.is_empty() {
+            return Err(CheckErrors::InvalidTypeDescription);
+        }
         let mut trait_signature: BTreeMap<ClarityName, FunctionSignature> = BTreeMap::new();
         let functions_types = type_args[0]
             .match_list()