fix(VirtualStream): Fix issue in VirtualStream to handle null values during data writing.

ts/classes.virtualstream.ts

@@ -399,11 +399,17 @@ export class VirtualStream<T = Uint8Array> implements plugins.typedRequestInterf
   public async writeToWebstream(writableStreamArg: WritableStream<T>) {
     const writer = writableStreamArg.getWriter();
     while(this.keepAlive || this.receiveBackpressuredArray.checkHasItems()) {
-      await writer.write(await this.fetchData());
+      const value = await this.fetchData();
+      if (value === null) {
+        writableStreamArg.close();
+        break;
+      }
+      await writer.write(value);
     }
   }
 
   public async close() {
+    this.sendData(null);
     this.keepAlive = false;
   }
 }