message: Only add `update-pr-from-base-branch` button if personal token is present
  Fixes
  Closes
diff: @@ -95,7 +95,9 @@ async function addButton(): Promise<void> {
  }
  }
  -function init(): void | false {
  +async function init(): Promise<void | false> {
  + await api.expectToken();
  +
  // Button exists when the current user can merge the PR.
  // Button is disabled when:
  // - There are conflicts (there's already a native "Resolve conflicts" button)
  