Added a getter in Mistake class to get the name. Resolved the non nul…

…l assertion issue as suggested by Yuri

lib/core/controllers/colored_text_editing_controller.dart

@@ -13,7 +13,7 @@ class ColoredTextEditingController extends TextEditingController {
  /// An [OverlayEntry] for the [Overlay] class.
  /// This entry represents the floating popup
  /// that appears on a mistake.
- OverlayEntry? overlayEntry;
+ OverlayEntry? _overlayEntry;
 
  /// Represents the maximum numbers of suggestions allowed.
  final int suggestionsLimit;
@@ -104,8 +104,7 @@ class ColoredTextEditingController extends TextEditingController {
  : mistake.replacements.sublist(0, suggestionsLimit);
 
  /// Parsing the mistake enum types to string type
- final String mistakeName =
- mistake.type.name[0].toUpperCase() + mistake.type.name.substring(1);
+ final String mistakeName = mistake.name;
 
  /// Mistake highlighted TextSpan
  yield TextSpan(
@@ -131,7 +130,7 @@ class ColoredTextEditingController extends TextEditingController {
  /// To remove overlay if present.
  _removeHighlightOverlay();
 
- overlayEntry = OverlayEntry(
+ final overlayEntry = OverlayEntry(
  builder: (BuildContext context) {
  return SuggestionsPopup(
  mistakeName: mistakeName,
@@ -153,9 +152,8 @@ class ColoredTextEditingController extends TextEditingController {
  },
  );
 
- Overlay.of(context).insert(
- overlayEntry ?? OverlayEntry(builder: (_) => Container()),
- );
+ _overlayEntry = overlayEntry;
+ Overlay.of(context).insert(overlayEntry);
  },
  text:
  text.substring(mistake.offset, mistake.offset + mistake.length),
@@ -183,8 +181,8 @@ class ColoredTextEditingController extends TextEditingController {
  }
 
  void _removeHighlightOverlay() {
- overlayEntry?.remove();
- overlayEntry = null;
+ _overlayEntry?.remove();
+ _overlayEntry = null;
  }
 
  /// Returns color for mistake TextSpan style

lib/domain/mistake.dart

@@ -19,6 +19,10 @@ class Mistake {
  /// Sorted by probability.
  final List<String> replacements;
 
+ /// Name of the mistake in string form.
+ /// The first letter will be capitalized
+ String get name => type.name[0].toUpperCase() + type.name.substring(1);
+
  /// Creates a new instance of the [Mistake] class.
  const Mistake({
  required this.message,