Improve create-report-index error reporting

[thibaudcolas]

I was trying out this project and stumbled upon this small thing – hope it helps! Currently create-report-index only logs error: undefined when it fails:

2021-01-04T14:59:53.649Z error: 	undefined

Changes

This change makes it log the error’s type and message, as well as the full stack trace. Sample output:

2021-01-04T15:01:15.332Z error: 	TypeError: Cannot read property '1' of null
TypeError: Cannot read property '1' of null
    at /cfgov-lighthouse/scripts/lib/reports.js:81:25
    at Array.map (<anonymous>)
    at processManifestRuns (/cfgov-lighthouse/scripts/lib/reports.js:76:15)
    at reducer (/cfgov-lighthouse/scripts/create-reports-index.js:59:27)
    at async /cfgov-lighthouse/scripts/create-reports-index.js:68:19

Testing

Manually add a throw new Error() somewhere inside the create-reports-index logic, and watch the command’s output before/after this change.

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows the standards laid out in the development playbook
• Passes all existing automated tests
• Any change in functionality is tested
• [ ] New functions are documented (with a description, list of inputs, and expected output)
• [ ] Placeholder code is flagged / future todos are captured in comments
• [ ] Visually tested in supported browsers and devices (see checklist below 👇)
• [ ] Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• [ ] Reviewers requested with the Reviewers tool ➡️

Testing checklist

Browsers

N/A

Accessibility

N/A

Other

• [ ] Is useable without CSS
• [ ] Is useable without JS
• [ ] Flexible from small to large screens
• No linting errors or warnings
• JavaScript tests are passing

[contolini]

Hey thanks @thibaudcolas!