refactor: modernize error handling with Go 1.26 errors.AsType

Replace errors.As with errors.AsType[T] for cleaner, type-safe error handling.
This leverages Go 1.26's generic error extraction API for improved code clarity.

Author: kaptinlin

errors.go

@@ -138,6 +138,6 @@ func NewErrRateLimit(retryAfter time.Duration) *ErrRateLimit {
 
 // IsErrRateLimit checks if the provided error is or wraps an ErrRateLimit error.
 func IsErrRateLimit(err error) bool {
-	var rateLimitErr *ErrRateLimit
-	return errors.As(err, &rateLimitErr)
+	_, ok := errors.AsType[*ErrRateLimit](err)
+	return ok
 }

tests/default_logger_test.go

@@ -37,7 +37,7 @@ func TestDefaultLoggerFatalExitsWithCode1(t *testing.T) {
 	// The subprocess should have exited with code 1.
 	require.Error(t, err, "expected Fatal to cause a non-zero exit")
 
-	var exitErr *exec.ExitError
-	require.True(t, errors.As(err, &exitErr), "expected *exec.ExitError")
+	exitErr, ok := errors.AsType[*exec.ExitError](err)
+	require.True(t, ok, "expected *exec.ExitError")
 	assert.Equal(t, 1, exitErr.ExitCode(), "expected exit code 1")
 }

tests/handler_test.go

@@ -84,6 +84,6 @@ func TestHandlerProcessWithRateLimiter(t *testing.T) {
 
 	// The second call should be limited
 	err = handler.Process(context.Background(), job)
-	var rateLimitError *queue.ErrRateLimit
-	assert.True(t, errors.As(err, &rateLimitError), "Process() should return ErrRateLimit error")
+	_, ok := errors.AsType[*queue.ErrRateLimit](err)
+	assert.True(t, ok, "Process() should return ErrRateLimit error")
 }

tests/ratelimit_test.go

@@ -200,8 +200,8 @@ func TestDualRateLimiterHandlerBlocksSecond(t *testing.T) {
 
 	// Second call should be rate-limited by the handler limiter.
 	err = handler.Process(context.Background(), job)
-	var rateLimitErr *queue.ErrRateLimit
-	require.True(t, errors.As(err, &rateLimitErr),
+	rateLimitErr, ok := errors.AsType[*queue.ErrRateLimit](err)
+	require.True(t, ok,
 		"second call should return ErrRateLimit from handler limiter")
 	assert.Equal(t, queue.DefaultRateLimitRetryAfter, rateLimitErr.RetryAfter,
 		"RetryAfter should match DefaultRateLimitRetryAfter")

worker.go

@@ -267,8 +267,7 @@ func (w *Worker) makeHandlerFunc(handler *Handler) func(ctx context.Context, tas
 
 // retryDelayFunc determines the delay before retrying a task after failure, using custom logic or falling back to Asynq's default.
 func (w *Worker) retryDelayFunc(count int, err error, task *asynq.Task) time.Duration {
-	var rateLimitErr *ErrRateLimit
-	if errors.As(err, &rateLimitErr) {
+	if rateLimitErr, ok := errors.AsType[*ErrRateLimit](err); ok {
 		return rateLimitErr.RetryAfter
 	}