Classic request for bower

It seems that npmjs plugin adds bower itself as dependency in yarn.lock… which doubles packages size. Is there a way to avoid this? Is it a bug? My snapcraft.yaml:

name: bower
version: 1.8.8
summary: A package manager for the web
description: Bower offers a generic, unopinionated solution to the problem of front-end package management
base: core18
confinement: classic
grade: stable
parts:
  bower:
    plugin: nodejs
    node-package-manager: yarn
    node-packages:
      - bower@1.8.8
    stage-packages:
      - openssl
      - curl
      - git
apps:
  bower:
    command: bin/bower
environment:
  GIT_EXEC_PATH: $SNAP/usr/lib/git-core