fix: validate hostname and improve errors

[pi0]

🔗 Linked issue

❓ Type of change

• [ ] 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• [ ] 🐞 Bug fix (a non-breaking change that fixes an issue)
• [ ] 👌 Enhancement (improving an existing functionality like performance)
• [ ] ✨ New feature (a non-breaking change that adds functionality)
• [ ] 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• [ ] ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Resolves #58

• Validate hostname (usually coming from a misconfigured environment) and throw an explicit error (to be improved as a soft error in #57)
• Use better warnings including tried host and port(s)

New errors:

• GetPortError: Invalid host: "http://localhost:8080"
• GetPortError: Unable to find any random port on host "192.168.1.999"
• GetPortError: Unable to find any available port on host "192.168.1.999" (tried 3000 and 3000-3100)

📝 Checklist

• [ ] I have linked an issue or discussion.
• [ ] I have updated the documentation accordingly.

[codecov[bot]]

Codecov Report

Merging #59 (ad58820) into main (8d48ec6) will increase coverage by 1.75%. The diff coverage is 84.78%.

:exclamation: Current head ad58820 differs from pull request most recent head f025e58. Consider uploading reports for the commit f025e58 to get more accurate results

@@            Coverage Diff             @@
##             main      #59      +/-   ##
==========================================
+ Coverage   84.63%   86.39%   +1.75%     
==========================================
  Files           2        2              
  Lines         319      338      +19     
  Branches       47       55       +8     
==========================================
+ Hits          270      292      +22     
+ Misses         49       46       -3     

Files Changed	Coverage Δ
src/index.ts	81.30% <84.78%> (+2.88%)	:arrow_up: