From eeb6ddc52a019dc1a2053cd5b7be8d6ad6186721 Mon Sep 17 00:00:00 2001
From: Philipp Hofmann <philipp.hofmann@sentry.io>
Date: Tue, 2 Jan 2024 13:54:42 +0100
Subject: [PATCH] fix: Crash when adding a crumb for a timezone change

Fix a crash when adding a time crumb for a timezone change and the
previously stored timezone offset is nil.

Fixes GH-3513
---
 CHANGELOG.md                                      |  1 +
 Sources/Sentry/SentrySystemEventBreadcrumbs.m     | 14 +++++++++-----
 .../SentrySystemEventBreadcrumbsTest.swift        | 15 +++++++++++++++
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 110234facbe..8abdbd4fada 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@
 
 - TTFD waits for next drawn frame (#3505)
 - Fix TTID/TTFD for app start transactions (#3512): TTID/TTFD spans and measurements for app start transaction now include the app start duration.
+- Crash when adding a crumb for a timezone change (#3524)
 
 ## 8.17.2
 
diff --git a/Sources/Sentry/SentrySystemEventBreadcrumbs.m b/Sources/Sentry/SentrySystemEventBreadcrumbs.m
index f482b9d725c..dcdb672e562 100644
--- a/Sources/Sentry/SentrySystemEventBreadcrumbs.m
+++ b/Sources/Sentry/SentrySystemEventBreadcrumbs.m
@@ -240,11 +240,15 @@ - (void)timezoneEventTriggered:(NSNumber *)storedTimezoneOffset
     NSInteger offset = SentryDependencyContainer.sharedInstance.dateProvider.timezoneOffset;
 
     crumb.type = @"system";
-    crumb.data = @{
-        @"action" : @"TIMEZONE_CHANGE",
-        @"previous_seconds_from_gmt" : storedTimezoneOffset,
-        @"current_seconds_from_gmt" : @(offset)
-    };
+
+    NSMutableDictionary *dataDict =
+        [@{ @"action" : @"TIMEZONE_CHANGE", @"current_seconds_from_gmt" : @(offset) } mutableCopy];
+
+    if (storedTimezoneOffset != nil) {
+        dataDict[@"previous_seconds_from_gmt"] = storedTimezoneOffset;
+    }
+
+    crumb.data = dataDict;
     [_delegate addBreadcrumb:crumb];
 
     [self updateStoredTimezone];
diff --git a/Tests/SentryTests/Integrations/Breadcrumbs/SentrySystemEventBreadcrumbsTest.swift b/Tests/SentryTests/Integrations/Breadcrumbs/SentrySystemEventBreadcrumbsTest.swift
index 71a18216e1c..ffc8ee4cdee 100644
--- a/Tests/SentryTests/Integrations/Breadcrumbs/SentrySystemEventBreadcrumbsTest.swift
+++ b/Tests/SentryTests/Integrations/Breadcrumbs/SentrySystemEventBreadcrumbsTest.swift
@@ -1,3 +1,4 @@
+import Nimble
 @testable import Sentry
 import SentryTestUtils
 import XCTest
@@ -251,6 +252,20 @@ class SentrySystemEventBreadcrumbsTest: XCTestCase {
             XCTAssertEqual(data["current_seconds_from_gmt"] as? Int64, 7_200)
         }
     }
+    
+    func testTimezoneChangeNotificationBreadcrumb_NoStoredTimezoneOffset() {
+        sut = fixture.getSut(currentDevice: nil)
+
+        fixture.currentDateProvider.timezoneOffsetValue = 7_200
+        fixture.fileManager.deleteTimezoneOffset()
+
+        sut.timezoneEventTriggered()
+
+        assertBreadcrumbAction(action: "TIMEZONE_CHANGE") { data in
+            expect(data["previous_seconds_from_gmt"]) == nil
+            expect(data["current_seconds_from_gmt"] as? Int64) == 7_200
+        }
+    }
 
     func testStopCallsSpecificRemoveObserverMethods() {
         sut = fixture.getSut(currentDevice: nil)