<alice@example.com> appears multiple times in the contributors file and could not be merged automatically:
  line 9: - Alice Smith <alice@example.com>
  line 11:   pairing with Alice Smith <alice@example.com>
To fix this:
1. Merge these entries in the contributors file manually, keeping a single line for <alice@example.com>.
2. If the same person contributed under several names, add an entry in 'aliases.json' so a single name is always used for this email, for example:
{
  "alice@example.com": {
    "mails": [
      "alice@example.com"
    ],
    "name": "Alice Smith"
  }
}
Then run contributors-txt again.
