fix(value): use-after-free in object merge (#1539)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: jpnurmi

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+**Fixes**:
+
+- Fix use-after-free on allocation failure when merging scope tags, extra, and contexts into a captured event. ([#1539](https://github.com/getsentry/sentry-native/pull/1539))
+
 ## 0.13.0
 
 **Breaking**:

src/sentry_value.c

@@ -1112,10 +1112,10 @@ sentry__value_merge_objects(sentry_value_t dst, sentry_value_t src)
                 return 1;
             }
         } else if (sentry_value_is_null(dst_val)) {
+            sentry_value_incref(src_val);
             if (sentry_value_set_by_key(dst, key, src_val) != 0) {
                 return 1;
             }
-            sentry_value_incref(src_val);
         }
     }
     return 0;