Merge branch 'version_4' of https://github.com/danvick/flutter_form_builder into version_4

Author: danvick

lib/src/fields/form_builder_color_picker.dart

@@ -212,7 +212,7 @@ class _FormBuilderColorPickerFieldState
 
   Future<void> _handleFocus() async {
     if (effectiveFocusNode.hasFocus && enabled) {
-      effectiveFocusNode?.unfocus();
+      effectiveFocusNode.unfocus();
       final selected = await showDialog<bool>(
         context: context,
         builder: (BuildContext context) {

lib/src/fields/form_builder_date_range_picker.dart

@@ -206,8 +206,8 @@ class FormBuilderDateRangePickerState
   }
 
   Future<void> _handleFocus() async {
-    effectiveFocusNode?.unfocus();
     if (effectiveFocusNode.hasFocus && enabled) {
+      effectiveFocusNode.unfocus();
       final initialFirstDate = value?.isEmpty ?? true
           ? (widget.initialFirstDate ?? DateTime.now())
           : value[0];