reintroduce existing code and add new function with needed behavior, to avoid breaking changes

Author: lreardon

lib/src/form_builder_field.dart

@@ -62,12 +62,10 @@ class FormBuilderField<T> extends FormField<T> {
   });
 
   @override
-  FormBuilderFieldState<FormBuilderField<T>, T> createState() =>
-      FormBuilderFieldState<FormBuilderField<T>, T>();
+  FormBuilderFieldState<FormBuilderField<T>, T> createState() => FormBuilderFieldState<FormBuilderField<T>, T>();
 }
 
-class FormBuilderFieldState<F extends FormBuilderField<T>, T>
-    extends FormFieldState<T> {
+class FormBuilderFieldState<F extends FormBuilderField<T>, T> extends FormFieldState<T> {
   String? _customErrorText;
   FormBuilderState? _formBuilderState;
   bool _touched = false;
@@ -83,21 +81,25 @@ class FormBuilderFieldState<F extends FormBuilderField<T>, T>
   /// Returns the initial value, which may be declared at the field, or by the
   /// parent [FormBuilder.initialValue]. When declared at both levels, the field
   /// initialValue prevails.
-  T? get initialValue =>
-      widget.initialValue ??
-      (_formBuilderState?.initialValue ??
-          const <String, dynamic>{})[widget.name] as T?;
+  T? get initialValue => widget.initialValue ?? (_formBuilderState?.initialValue ?? const <String, dynamic>{})[widget.name] as T?;
 
   dynamic get transformedValue => widget.valueTransformer?.call(value) ?? value;
 
   @override
   String? get errorText => super.errorText ?? _customErrorText;
 
+  @override
+  bool get hasError => super.hasError || errorText != null;
+
+  @override
+  bool get isValid => super.isValid && errorText == null;
+
+  bool get isValueValid => super.isValid;
+  bool get valueHasError => super.hasError;
+
   bool get enabled => widget.enabled && (_formBuilderState?.enabled ?? true);
   bool get readOnly => !(_formBuilderState?.widget.skipDisabled ?? false);
-  bool get _isAlwaysValidate =>
-      widget.autovalidateMode.isAlways ||
-      (_formBuilderState?.widget.autovalidateMode?.isAlways ?? false);
+  bool get _isAlwaysValidate => widget.autovalidateMode.isAlways || (_formBuilderState?.widget.autovalidateMode?.isAlways ?? false);
 
   /// Will be true if the field is dirty
   ///
@@ -233,14 +235,9 @@ class FormBuilderFieldState<F extends FormBuilderField<T>, T>
     }
     final isValid = super.validate() && !hasError;
 
-    final fields = _formBuilderState?.fields ??
-        <String, FormBuilderFieldState<FormBuilderField<dynamic>, dynamic>>{};
+    final fields = _formBuilderState?.fields ?? <String, FormBuilderFieldState<FormBuilderField<dynamic>, dynamic>>{};
 
-    if (!isValid &&
-        focusOnInvalid &&
-        (formState?.focusOnInvalid ?? true) &&
-        enabled &&
-        !fields.values.any((e) => e.effectiveFocusNode.hasFocus)) {
+    if (!isValid && focusOnInvalid && (formState?.focusOnInvalid ?? true) && enabled && !fields.values.any((e) => e.effectiveFocusNode.hasFocus)) {
       focus();
       if (autoScrollWhenFocusOnInvalid) ensureScrollableVisibility();
     }