build: fix Cannot read properties of undefined in generate-docs.js

[sjinks]

Description

/home/runner/work/vip-cli/vip-cli/helpers/generate-docs.js:89
			while ( ! lines[ lineIx ].trim().startsWith( '$' ) ) {
			                          ^

TypeError: Cannot read properties of undefined (reading 'trim')
    at parseOutput (/home/runner/work/vip-cli/vip-cli/helpers/generate-docs.js:89:30)
    at processCommand (/home/runner/work/vip-cli/vip-cli/helpers/generate-docs.js:118:23)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async processCommand (/home/runner/work/vip-cli/vip-cli/helpers/generate-docs.js:126:24)
    at async main (/home/runner/work/vip-cli/vip-cli/helpers/generate-docs.js:144:17)

Node.js v18.20.2

This PR fixes that error.

Ref: https://github.com/Automattic/vip-cli/actions/runs/8822638714/job/24221295810

Pull request checklist

• Update SETUP.md with any new environmental variables.
• Update the documentation.
• Manually test the relevant changes.
• Follow the pull request checklist
• Add/update automated tests as needed.

New release checklist

• Automated tests pass.
• The Preparing for release checklist is completed.

Steps to Test

Check out the PR and verify that node helpers/generate-docs.js works as expected.

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Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

OpenSSF Scorecard

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Scanned Manifest Files

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud