Update error_cause to RFC 9260

[philipch07]

Description

• Updated error_cause.go to have updated errors according to RFC 9260
• Added an error for other causes if the length is too short
• Added references to RFC 9260 where applicable

Reference issue

Resolves #424.

[codecov]

Codecov Report

❌ Patch coverage is 78.94737% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.57%. Comparing base (a69c6a2) to head (22bf9a2).
⚠️ Report is 26 commits behind head on master.

Files with missing lines	Patch %	Lines
error_cause.go	88.88%	0 Missing and 1 partial ⚠️
error_cause_protocol_violation.go	50.00%	0 Missing and 1 partial ⚠️
error_cause_unrecognized_chunk_type.go	0.00%	0 Missing and 1 partial ⚠️
error_cause_user_initiated_abort.go	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #425      +/-   ##
==========================================
+ Coverage   83.84%   84.57%   +0.72%     
==========================================
  Files          51       51              
  Lines        3448     3455       +7     
==========================================
+ Hits         2891     2922      +31     
+ Misses        417      394      -23     
+ Partials      140      139       -1     

Flag	Coverage Δ
go	84.57% <78.94%> (+0.72%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Copilot]

Pull Request Overview

This PR enhances error cause handling in the SCTP implementation by adding validation for error cause lengths and improving code consistency. The changes ensure that error causes comply with RFC 9260 specifications regarding the 16-bit length field constraints.

• Adds length validation to prevent oversized error cause values that would overflow the 16-bit length field
• Refactors error handling to use inline variable declarations for cleaner code
• Updates documentation and error messages for clarity and RFC 9260 compliance

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
error_cause.go	Adds pre-validation in buildErrorCause(), introduces new error constants, updates error messages, and fixes String() method capitalization
error_cause_header.go	Adds length validation in marshal(), adds input validation in unmarshal(), improves inline comments, and defines maxErrorCauseValueLen constant
error_cause_user_initiated_abort.go	Adds length validation in marshal() using new constant, refactors unmarshal error handling, fixes comment spacing
error_cause_protocol_violation.go	Adds length validation in marshal() using new constant, refactors unmarshal error handling, updates documentation formatting
error_cause_unrecognized_chunk_type.go	Refactors unmarshal error handling to inline variable declaration

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.