fix(options): reject nil annotation key in WithAnnotation

Author: tigerwill90

options.go

@@ -321,6 +321,9 @@ func WithClientIPResolver(resolver ClientIPResolver) interface {
 // packages that use route annotation.
 func WithAnnotation(key, value any) RouteOption {
 	return optionFunc(func(s sealedOption) error {
+		if key == nil {
+			return fmt.Errorf("%w: annotation key is nil", ErrInvalidConfig)
+		}
 		if !reflect.TypeOf(key).Comparable() {
 			return fmt.Errorf("%w: annotation key is not comparable", ErrInvalidConfig)
 		}

options_test.go

@@ -762,6 +762,7 @@ func TestWithAnnotation_Invalid(t *testing.T) {
 	f, err := NewRouter()
 	require.NoError(t, err)
 	assert.ErrorIs(t, onlyError(f.Add(MethodGet, "/foo/{bar}", emptyHandler, WithAnnotation(nonComparableKey, nil))), ErrInvalidConfig)
+	assert.ErrorIs(t, onlyError(f.Add(MethodGet, "/foo/{bar}", emptyHandler, WithAnnotation(nil, "value"))), ErrInvalidConfig)
 }
 
 func TestWithQueryMatcher(t *testing.T) {