fix(ttfd): measurements should only be added for successful ttfd

CHANGELOG.md

@@ -66,6 +66,7 @@ Navigator.push(
 - Start missing TTFD for root screen transaction ([#2332](https://github.com/getsentry/sentry-dart/pull/2332))
 - Accessing invalid json fields from `fetchNativeAppStart` should return null ([#2340](https://github.com/getsentry/sentry-dart/pull/2340))
 - Error when calling `SentryFlutter.reportFullyDisplayed()` twice ([#2339](https://github.com/getsentry/sentry-dart/pull/2339))
+- TTFD measurements should only be added for successful TTFD spans ([#2348](https://github.com/getsentry/sentry-dart/pull/2348))
 
 ### Deprecate
 

flutter/lib/src/navigation/time_to_full_display_tracker.dart

@@ -71,7 +71,7 @@
     final endTimestamp = timestamp ?? _endTimestampProvider();
 
     if (ttfdSpan == null ||
-        ttfdSpan.finished == true ||
+        ttfdSpan.finished ||
         startTimestamp == null ||
         endTimestamp == null) {
       options.logger(
@@ -83,14 +83,29 @@
       return;
     }
 
-    _setTTFDMeasurement(startTimestamp, endTimestamp);
-    await ttfdSpan.finish(
-      status:
-          timestamp != null ? SpanStatus.ok() : SpanStatus.deadlineExceeded(),
-      endTimestamp: endTimestamp,
-    );
-    _completedTTFDTracking.complete();
-    clear();
+    // If a timestamp is provided, the operation was successful; otherwise, it timed out
+    final status =
+        timestamp != null ? SpanStatus.ok() : SpanStatus.deadlineExceeded();
+    try {
+      // Should only add measurements if the span is successful
+      if (status == SpanStatus.ok()) {
+        _setTTFDMeasurement(startTimestamp, endTimestamp);
+      }
+      await ttfdSpan.finish(
+        status: status,
+        endTimestamp: endTimestamp,
+      );
+    } catch (e, stackTrace) {
+      options.logger(
+        SentryLevel.error,
+        'Failed to finish TTFD span',
+        exception: e,
+        stackTrace: stackTrace,
+      );
+    } finally {
+      _completedTTFDTracking.complete();
+      clear();
+    }
   }
 
   void _setTTFDMeasurement(DateTime startTimestamp, DateTime endTimestamp) {

flutter/test/navigation/time_to_full_display_tracker_test.dart

@@ -44,6 +44,7 @@ void main() {
     final differenceInSeconds =
         actualEndTimestamp.difference(expectedEndTimestamp).inSeconds.abs();
     expect(differenceInSeconds, lessThanOrEqualTo(1));
+    expect(transaction.measurements, isNotEmpty);
   });
 
   test(
@@ -66,6 +67,7 @@ void main() {
     expect(ttfdSpan.status, equals(SpanStatus.deadlineExceeded()));
     expect(ttfdSpan.context.description, equals('Current route full display'));
     expect(ttfdSpan.origin, equals(SentryTraceOrigins.manualUiTimeToDisplay));
+    expect(transaction.measurements, isEmpty);
   });
 
   test('finishing ttfd twice does not throw', () async {