improvement: check for SentryTracer type in TTID (#2497)

* fix

* update

* update CHANGELOG

Author: buenaflor

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+### Improvements
+
+- Check for type before casting in TTID ([#2497](https://github.com/getsentry/sentry-dart/pull/2497))
 
 ### Fixes 
 

flutter/lib/src/navigation/time_to_initial_display_tracker.dart

@@ -51,11 +51,13 @@ class TimeToInitialDisplayTracker {
     final _endTimestamp = endTimestamp ?? await determineEndTime();
     if (_endTimestamp == null) return;
 
-    final tracer = transaction as SentryTracer;
+    if (transaction is! SentryTracer) {
+      return;
+    }
 
     final ttidSpan = transaction.startChild(
       SentrySpanOperations.uiTimeToInitialDisplay,
-      description: '${tracer.name} initial display',
+      description: '${transaction.name} initial display',
       startTimestamp: startTimestamp,
     );