chore: standardize errors (CN-944)

[ividalATSnyk]

• Ready for review
• Follows CONTRIBUTING rules
• Reviewed by Snyk internal team

What does this PR do?

• standardize error handling

Where should the reviewer start?

Our core change was adding lib/error-utils.ts, which exports a getErrorMessage(error: unknown): string utility. From there, we migrated all ~21 unsafe catch blocks across lib/ to use it, replacing direct .message/.stack accesses on unverified catch variables, and flipped useUnknownInCatchVariables to true in tsconfig.json so the compiler enforces this going forward.

What are the relevant tickets?

CN-944

[snyk-pr-review-bot]

PR Reviewer Guide 🔍

🧪 PR contains tests

🔒 No security concerns identified

⚡ No major issues detected

📚 Repository Context Analyzed This review considered 39 relevant code sections from 13 files (average relevance: 0.96) lib/go-parser/go-binary.ts (lines 1-211) lib/analyzer/applications/python/pip.ts (lines 1-179) lib/extractor/index.ts (2 segments, lines 1-233) lib/scan.ts (2 segments, lines 1-247) lib/dockerfile/instruction-parser.ts (lines 1-247) lib/extractor/docker-archive/layer.ts (lines 1-143) lib/dockerfile/index.ts (lines 1-61) ... and 6 more file(s)