fix: 🐛 Ignore extra _nextIfAny function operations as showcase mayb…

…e discarded at time of next call (#410)

- Added `isShowCaseCompleted` getter to check the showcase is completed or not
- If the showcase is already completed no need to further process the `_nextIfAny` function operations and we will stop execution of this function. This may happen if a user taps very fast and lots of time on the showcase barrier

lib/src/showcase.dart

@@ -474,6 +474,8 @@ class _ShowcaseState extends State<Showcase> {
   }
 
   Future<void> _nextIfAny() async {
+    if (showCaseWidgetState.isShowCaseCompleted) return;
+
     if (timer != null && timer!.isActive) {
       if (showCaseWidgetState.enableAutoPlayLock) {
         return;
@@ -483,6 +485,7 @@ class _ShowcaseState extends State<Showcase> {
       timer = null;
     }
     await _reverseAnimateTooltip();
+    if (showCaseWidgetState.isShowCaseCompleted) return;
     showCaseWidgetState.completed(widget.key);
   }
 

lib/src/showcase_widget.dart

@@ -145,6 +145,8 @@ class ShowCaseWidgetState extends State<ShowCaseWidget> {
 
   bool get enableShowcase => widget.enableShowcase;
 
+  bool get isShowCaseCompleted => ids == null && activeWidgetId == null;
+
   /// Returns value of [ShowCaseWidget.blurValue]
   double get blurValue => widget.blurValue;