fix(bind): return an error for a destination that is not a pointer

bind.go

@@ -216,12 +216,19 @@ func bindMetaFor(typ reflect.Type) *bindStructMeta {
 
 // bindData will bind data ONLY fields in destination struct that have EXPLICIT tag
 func bindData(destination any, data map[string][]string, tag string, dataFiles map[string][]*multipart.FileHeader) error {
-	if destination == nil || (len(data) == 0 && len(dataFiles) == 0) {
+	if destination == nil {
 		return nil
 	}
 	hasFiles := len(dataFiles) > 0
-	typ := reflect.TypeOf(destination).Elem()
-	val := reflect.ValueOf(destination).Elem()
+	rv := reflect.ValueOf(destination)
+	if rv.Kind() != reflect.Pointer || rv.IsNil() {
+		return errors.New("binding destination must be a non-nil pointer")
+	}
+	if len(data) == 0 && len(dataFiles) == 0 {
+		return nil
+	}
+	typ := rv.Type().Elem()
+	val := rv.Elem()
 
 	// Support binding to limited Map destinations:
 	// - map[string][]string,

bind_test.go

@@ -249,6 +249,28 @@ func TestBindQueryParams(t *testing.T) {
 	}
 }
 
+func TestBindQueryParamsToNonPointer(t *testing.T) {
+	e := New()
+	req := httptest.NewRequest(http.MethodGet, "/?id=1", nil)
+	rec := httptest.NewRecorder()
+	c := e.NewContext(req, rec)
+
+	// Binding into a value instead of a pointer must return an error and must
+	// not panic.
+	var err error
+	assert.NotPanics(t, func() {
+		err = c.Bind(user{})
+	})
+	assert.ErrorContains(t, err, "binding destination must be a non-nil pointer")
+
+	// The error is reported as a bad request, the same way the JSON binder
+	// reports a destination that is not a pointer.
+	var httpErr *HTTPError
+	if assert.ErrorAs(t, err, &httpErr) {
+		assert.Equal(t, http.StatusBadRequest, httpErr.Code)
+	}
+}
+
 func TestBindQueryParamsCaseInsensitive(t *testing.T) {
 	e := New()
 	req := httptest.NewRequest(http.MethodGet, "/?ID=1&NAME=Jon+Snow", nil)