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go.error_type_assertion

Correctness Medium

Detects error type assertions using direct type assertion instead of errors.As().

Why It Matters

Direct type assertions on errors:

Miss wrapped errors — Wrapped errors don’t match direct type checks
Break error chains — Go 1.13+ error wrapping is ignored
Lose error context — Miss errors wrapped with fmt.Errorf("%w")

Example

// ❌ Before (misses wrapped errors)
if e, ok := err.(*MyError); ok {
    handleMyError(e)
}

// ✅ After (handles wrapped errors)
var myErr *MyError
if errors.As(err, &myErr) {
    handleMyError(myErr)
}

What Unfault Detects

err.(*Type) type assertions
switch err.(type) without unwrapping
Missing errors.As() for custom error types

Auto-Fix

Unfault replaces type assertions with errors.As():

var e *MyError
if errors.As(err, &e) {
    // ...
}