fix: add nil checks for native jsonResponse

Author: uerceg

Assets/Adjust/Native/iOS/AdjustUnity.mm

@@ -372,12 +372,13 @@ void _AdjustGetAttribution(AdjustDelegateAttributionGetter callback) {
             addValueOrEmpty(dictionary, @"costType", attribution.costType);
             addValueOrEmpty(dictionary, @"costAmount", attribution.costAmount);
             addValueOrEmpty(dictionary, @"costCurrency", attribution.costCurrency);
-
-            NSData *jsonData = [NSJSONSerialization dataWithJSONObject:attribution.jsonResponse 
-                                                               options:0
-                                                                 error:nil];
-            NSString *strJsonResponse = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
-            addValueOrEmpty(dictionary, @"jsonResponse", strJsonResponse);
+            if (attribution.jsonResponse != nil) {
+                NSData *jsonData = [NSJSONSerialization dataWithJSONObject:attribution.jsonResponse 
+                                                                   options:0
+                                                                     error:nil];
+                NSString *strJsonResponse = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
+                addValueOrEmpty(dictionary, @"jsonResponse", strJsonResponse);
+            }
 
             NSData *dataAttribution = [NSJSONSerialization dataWithJSONObject:dictionary
                                                                       options:0

Assets/Adjust/Native/iOS/AdjustUnityDelegate.mm

@@ -124,13 +124,15 @@ - (void)adjustAttributionChangedWannabe:(ADJAttribution *)attribution {
                    forKey:@"costCurrency"
              toDictionary:dictionary];
 
-    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:attribution.jsonResponse 
-                                                       options:0
-                                                         error:nil];
-    NSString *strJsonResponse = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
-    [self addValueOrEmpty:strJsonResponse
-                   forKey:@"jsonResponse"
-             toDictionary:dictionary];
+    if (attribution.jsonResponse != nil) {
+        NSData *jsonData = [NSJSONSerialization dataWithJSONObject:attribution.jsonResponse 
+                                                           options:0
+                                                             error:nil];
+        NSString *strJsonResponse = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
+        [self addValueOrEmpty:strJsonResponse
+                       forKey:@"jsonResponse"
+                 toDictionary:dictionary];
+    }
 
     NSData *dataAttribution = [NSJSONSerialization dataWithJSONObject:dictionary
                                                               options:0