bug: reduce of empty value

[scottnath]

When running semantic release on modules with an issue with their commit history, then the missing array causes a bug which may be blocking the release to npm process.

Steps for Reproducing

• trigger a build on #58 in eslint-config-punchcard in travis
• view the log for semantic release
• see the error

Error:

npm run semantic-release
> eslint-config-punchcard@ semantic-release /home/travis/build/punchcard-cms/eslint-config-punchcard
> semantic-release pre && npm publish && semantic-release post
/home/travis/build/punchcard-cms/eslint-config-punchcard/node_modules/punchcard-semantic-release/analyze.js:82
  }).sort().reduce((prev, curr) => {
            ^
TypeError: Reduce of empty array with no initial value

[joshkimmell]

@scottnath to research if this is fixed or not. If not, please estimate and we'll discuss at grooming.