Improve error reporting for repository reference with `@`

[jsoref]

This actually happened as someone was migrating from:

  steps:
  - uses: owner/repo@ref

to:

  steps:
  - uses: actions/checkout@v4
    with:
      repository: owner/repo@ref
      ssh-key: ${{ secrets.OWNER_REPO_KEY }}
  - uses: ./

There are two flavors of poor error messages here.

Annotations

1 error

❌ checkout
Not Found

Workflow: https://github.com/check-spelling-sandbox/checkout-repository-with-at/actions/runs/8297497838/workflow

name: checkout repository with at

on:
  push:

jobs:
  checkout:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4
        with:
          repository: check-spelling-sandbox/checkout-repository-with-at@main

Annotations

4 errors

❌ checkout
remote error:
❌ checkout
remote error:
❌ checkout
remote error:
❌ checkout
The process '/usr/bin/git' failed with exit code 128

Workflow: https://github.com/check-spelling-sandbox/checkout-repository-with-at/actions/runs/8297497848/workflow

name: checkout repository with at (private)

on:
  push:

jobs:
  checkout:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4
        with:
          repository: check-spelling-sandbox/checkout-repository-with-at@main
          ssh-key: ${{ secrets.REPO_KEY }}