Action fails with "Error: Reduce of empty array with no initial value"

[ajalt]

I have a Keep A Changelog formatted CHANGELOG.md file; running this action with all default settings fails with

Error: Reduce of empty array with no initial value

Here is the job and relevant files:

Failed run: https://github.com/ajalt/colormath/actions/runs/8727198863/job/23944191785 Workflow file: https://github.com/ajalt/colormath/blob/4a0cc9796c743cb4965407204ee63b40aaf22fca/.github/workflows/release.yml#L25-L27 Changelog: https://github.com/ajalt/colormath/blob/4a0cc9796c743cb4965407204ee63b40aaf22fca/CHANGELOG.md?plain=1