Code review feedback.

Author: tjprescott

packages/versioning/src/validate.ts

@@ -169,8 +169,9 @@ export function $onValidate(program: Program) {
  */
 function validateVersionEnumValuesUnique(program: Program, namespace: Namespace) {
   const [_, versionMap] = getVersions(program, namespace);
-  const size = versionMap?.size;
-  const values = new Set(versionMap?.getVersions().map((v) => v.value));
+  if (versionMap === undefined) return;
+  const size = versionMap.size;
+  const values = new Set(versionMap.getVersions().map((v) => v.value));
   if (size && values) {
     if (size !== values.size) {
       const enumName = versionMap.getVersions()[0].enumMember.enum.name;