There is currently an erroneous component array (rather than object) in alpha that has been fixed by #1206, but not tagged and distributed. I am currently incorporating this fix by installing BV alpha via github branch:

{
  "dependencies": {
    "bootstrap-vue": "git://github.com/bootstrap-vue/bootstrap-vue.git#alpha"
  }
}

This is okay, but not ideal in the event that alpha gets updated (non deterministic build). If this alpha release has been frozen, it should receive a stability release, git tag, and npm release.