message: chore(types): remove unnecessary type assertion
diff: @@ -221,7 +221,7 @@ function doWatch(
  } else if (isFunction(source)) {
  if (cb) {
  // getter with cb
  - getter = () => call(source as Function, WATCHER_GETTER)
  + getter = () => call(source, WATCHER_GETTER)
  } else {
  // no cb -> simple effect
  getter = () => {
  @@ -231,7 +231,7 @@ function doWatch(
  if (cleanup) {
  cleanup()
  }
  - return call(source as Function, WATCHER, [onCleanup])
  + return call(source, WATCHER, [onCleanup])
  }
  }
  } else {
  