exception-handler.interceptor.md

Exception Handler Interceptor

Interceptor that catches all errors in the request pipeline. Its job is to sanitize errors and finalize tracing before passing to the Exception Filter.

What It Does

1. Catches any error from the request pipeline
2. Sanitizes external API errors (Axios)
3. Adds context (class/method where error occurred)
4. Finalizes tracing with error status
5. Re-throws to Exception Filter

Tracing Lifecycle

Step	Where	Tracing Action
1	Request arrives	tracing.start()
2	Processing...	tracing.addAttribute()
3	Error occurs	Interceptor catches
4	This interceptor	tracing.setStatus(ERROR)
5	This interceptor	tracing.finish() ✓
6	Exception Filter	Formats response

Error Sanitization

Axios errors are sanitized to expose a consistent interface:

// Before: Raw Axios error with nested response
error.response.data.error.message

// After: Sanitized with getResponse() and getStatus()
error.getResponse()  // Returns error data
error.getStatus()    // Returns status code

Status Code Resolution

// Priority order for status code:
1. error.response.data.error.code (nested)
2. error.response.data.code
3. error.response.status
4. error.status
5. 500 (fallback)

Summary

Feature	Description
Purpose	Catch errors, finalize tracing
Sanitizes	Axios external API errors
Adds	traceid, context
Finalizes	Tracing span with ERROR status

Exception Handler Interceptor - Error pipeline that closes tracing spans.