message: refactor: set should return early if original def has getter but no setter
diff: @@ -179,6 +179,8 @@ export function defineReactive (
  if (process.env.NODE_ENV !== 'production' && customSetter) {
  customSetter()
  }
  + // #7981: for accessor properties without setter
  + if (getter && !setter) return
  if (setter) {
  setter.call(obj, newVal)
  } else {
  