refactor: addess review

Co-authored-by: Aaron Blankstein <[email protected]>

Author: hugoclrd

clarity/src/vm/types/signatures.rs

@@ -1655,11 +1655,10 @@ 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]
+        let functions_types = type_args
+               .get(0)
+               .ok_or_else(|| CheckErrors::InvalidTypeDescription)?       
             .match_list()
             .ok_or(CheckErrors::DefineTraitBadSignature)?;