fix(sentry): resolve minified exception types on web release

lib/features/thread_detail/presentation/extension/labels/add_label_to_thread_extension.dart

@@ -112,7 +112,7 @@ extension AddLabelToThreadExtension on ThreadDetailController {
       consumeState(
         Stream.value(Left(
           AddALabelToAThreadFailure(
-            exception: LabelKeywordIsNull(),
+            exception: const LabelKeywordIsNull(),
             labelDisplay: labelDisplay,
           ),
         )),

lib/features/thread_detail/presentation/extension/labels/remove_label_from_thread_extension.dart

@@ -44,7 +44,7 @@ extension RemoveLabelFromThreadExtension on ThreadDetailController {
       emitFailure(
         controller: this,
         failure: RemoveALabelFromAThreadFailure(
-          exception: LabelKeywordIsNull(),
+          exception: const LabelKeywordIsNull(),
           labelDisplay: labelDisplay,
         ),
       );