Fix circular reference JSON serialization in telemetry logging (#4150)

packages/core/src/utils/safeJsonStringify.ts

@@ -0,0 +1,32 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Safely stringifies an object to JSON, handling circular references by replacing them with [Circular].
+ *
+ * @param obj - The object to stringify
+ * @param space - Optional space parameter for formatting (defaults to no formatting)
+ * @returns JSON string with circular references replaced by [Circular]
+ */
+export function safeJsonStringify(
+  obj: unknown,
+  space?: string | number,
+): string {
+  const seen = new WeakSet();
+  return JSON.stringify(
+    obj,
+    (key, value) => {
+      if (typeof value === 'object' && value !== null) {
+        if (seen.has(value)) {
+          return '[Circular]';
+        }
+        seen.add(value);
+      }
+      return value;
+    },
+    space,
+  );
+}