refactor: remove use of structuredClone()

Author: mikuso

lib/client.js

@@ -406,10 +406,12 @@ class RPCClient extends EventEmitter {
         this._connectPromise = (async () => {
             this._wsAbortController = new AbortController();
 
-            const wsOpts = structuredClone(this._options.wsOpts ?? {});
-            wsOpts.noDelay = true;
-            wsOpts.signal = this._wsAbortController.signal;
-            wsOpts.headers = wsOpts.headers ?? {};
+            const wsOpts = Object.assign({}, {
+                // defaults
+                noDelay: true,
+                signal: this._wsAbortController.signal,
+                headers: {},
+            }, this._options.wsOpts ?? {});
 
             Object.assign(wsOpts.headers, this._options.headers);