fix(browser): ensure proxy is defined

src/lib/connect/ws.ts

@@ -260,7 +260,7 @@ const browserStreamBuilder: StreamBuilder = (client, opts) => {
 		let { data } = event
 		if (data instanceof ArrayBuffer) data = Buffer.from(data)
 		else data = Buffer.from(data as string, 'utf8')
-		if (!proxy?.destroyed) {
+		if (proxy && !proxy.destroyed) {
 			proxy.push(data)
 		}
 	}