diff --git a/Configs/Module-Debug.xcconfig b/Configs/Module-Debug.xcconfig
index dd4e5682b..e50d1b275 100644
--- a/Configs/Module-Debug.xcconfig
+++ b/Configs/Module-Debug.xcconfig
@@ -23,6 +23,9 @@ ENABLE_NS_ASSERTIONS = YES
 // When this setting is activated, the product will be built with options appropriate for running automated tests, such as making private interfaces accessible to the tests.
 ENABLE_TESTABILITY = YES
 
+// Check for violations of nullability annotations in function calls, return statements, and assignments.
+CLANG_UNDEFINED_BEHAVIOR_SANITIZER_NULLABILITY = YES
+
 // Specifies the degree to which the generated code is optimized for speed and binary size.
 GCC_OPTIMIZATION_LEVEL = 0
 
diff --git a/Sources/CocoaLumberjack/DDFileLogger.m b/Sources/CocoaLumberjack/DDFileLogger.m
index b18931a73..1a78724fd 100644
--- a/Sources/CocoaLumberjack/DDFileLogger.m
+++ b/Sources/CocoaLumberjack/DDFileLogger.m
@@ -1081,6 +1081,9 @@ - (DDLogFileInfo *)lt_currentLogFileInfo {
                      @"Invalid log file manager! Responds neither to `-createNewLogFileWithError:` nor `-createNewLogFile`!");
             currentLogFilePath = [_logFileManager createNewLogFile];
             #pragma clang diagnostic pop
+            if (!currentLogFilePath) {
+                NSLogError(@"DDFileLogger: Failed to create new log file");
+            }
         }
         // Use static factory method here, since it checks for nil (and is unavailable to Swift).
         _currentLogFileInfo = [DDLogFileInfo logFileWithPath:currentLogFilePath];
@@ -1325,6 +1328,8 @@ - (void)lt_logData:(NSData *)data {
     }
 
     @try {
+        NSFileHandle *handle = [self lt_currentLogFileHandle];
+
         if (implementsDeprecatedWillLog) {
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
@@ -1334,7 +1339,6 @@ - (void)lt_logData:(NSData *)data {
             [self willLogMessage:_currentLogFileInfo];
         }
 
-        NSFileHandle *handle = [self lt_currentLogFileHandle];
         if (@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)) {
             __autoreleasing NSError *error = nil;
             BOOL success = [handle seekToEndReturningOffset:nil error:&error];