Formatting and dart analyze fixes

example/lib/main.dart

@@ -68,7 +68,7 @@ class _MyHomePageState extends State<MyHomePage> {
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,
           children: <Widget>[
-            Text(
+            const Text(
               'Enter your card details below:',
             ),
             CardTextField(

lib/card_details.dart

@@ -37,7 +37,6 @@ class CardDetails {
   int _lastCheckHash = 0;
   CardProvider? provider;
 
-
   /// Checks the validity of the `CardDetails` and returns the result.
   ValidState get validState {
     checkIsValid();
@@ -59,7 +58,7 @@ class CardDetails {
   }
 
   /// The maximum length of the INN (identifier)
-  /// of a card provider. 
+  /// of a card provider.
   int get maxINNLength => 4;
 
   /// Validates each field of the `CardDetails` object in entry order,
@@ -265,11 +264,11 @@ enum CardProviderID {
 
 /// Encapsulates criteria for Card Providers in the U.S.
 /// Used by `CardDetails.detectCardProvider()` to determine
-/// a card's Provider. 
+/// a card's Provider.
 class CardProvider {
   CardProviderID id;
   List<int>? innValidNums;
-  List<_Range>? innValidRanges;
+  List<Range>? innValidRanges;
   int cardLength;
   int cvcLength;
 
@@ -289,12 +288,12 @@ class CardProvider {
 
 /// Object for `CardProvider` to determine valid number ranges.
 /// A loose wrapper on a tuple, that provides assertion of
-/// valid inputs and the `isWithin()` helper function. 
-class _Range {
+/// valid inputs and the `isWithin()` helper function.
+class Range {
   int high;
   int low;
 
-  _Range({required this.low, required this.high}) {
+  Range({required this.low, required this.high}) {
     assert(low <= high);
   }
 
@@ -328,7 +327,7 @@ List<CardProvider> _providers = [
     cardLength: 16,
     cvcLength: 3,
     innValidNums: [60, 65],
-    innValidRanges: [_Range(low: 644, high: 649)],
+    innValidRanges: [Range(low: 644, high: 649)],
   ),
   CardProvider(
     id: CardProviderID.jcb,
@@ -340,7 +339,7 @@ List<CardProvider> _providers = [
     id: CardProviderID.mastercard,
     cardLength: 16,
     cvcLength: 3,
-    innValidRanges: [_Range(low: 22, high: 27), _Range(low: 51, high: 55)],
+    innValidRanges: [Range(low: 22, high: 27), Range(low: 51, high: 55)],
   ),
   CardProvider(
     id: CardProviderID.visa,

lib/stripe_native_card_field.dart

@@ -31,8 +31,9 @@ class CardTextField extends StatefulWidget {
 
   final InputDecoration? inputDecoration; // TODO unapplied style
   final BoxDecoration? boxDecoration; // TODO unapplied style
-  final BoxDecoration? errorBoxDecoration; // TODO unapplied style 
+  final BoxDecoration? errorBoxDecoration; // TODO unapplied style
   final double width;
+
   /// Callback that returns the completed CardDetails object
   final void Function(CardDetails) onCardDetailsComplete;
   final double? height;
@@ -403,7 +404,7 @@ class CardTextFieldState extends State<CardTextField> {
   }
 
   /// Used when `_isWideFormat == false`, scrolls
-  /// the `_horizontalScrollController` to a given offset 
+  /// the `_horizontalScrollController` to a given offset
   void _scrollRow(CardEntryStep step) {
     const dur = Duration(milliseconds: 150);
     const cur = Curves.easeOut;
@@ -515,7 +516,7 @@ class CardNumberInputFormatter implements TextInputFormatter {
 }
 
 /// Formatter that adds a backslash '/' character in between
-/// the month and the year for the expiration date. 
+/// the month and the year for the expiration date.
 class CardExpirationFormatter implements TextInputFormatter {
   @override
   TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {