Request object does not contain postData for file/blob

[derevnjuk]

Stack trace
An output of execution with NODE_DEBUG=cypress-har-generator in the environment:

CYPRESS-HAR-GENERATOR 71195: The plugin receives from the CDP: {"method":"Network.requestWillBeSent","params":{"requestId":"72375.67","loaderId":"01E5D63DAE7FA33CD7871A317421E97E","documentURL":"http://localhost:8080/pages/post-data","request":{"url":"http://localhost:8080/api/echo","method":"POST","headers":{"sec-ch-ua":"","sec-ch-ua-platform":"","Referer":"http://localhost:8080/pages/post-data","sec-ch-ua-mobile":"?0","User-Agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/110.0.5481.177 Safari/537.36","Content-Type":"text/xml"},"hasPostData":true,"mixedContentType":"none","initialPriority":"High","referrerPolicy":"strict-origin-when-cross-origin","isSameSite":true},"timestamp":840585.128002,"wallTime":1678194739.973578,"initiator":{"type":"script","stack":{"callFrames":[{"functionName":"","scriptId":"20","url":"http://localhost:8080/pages/post-data","lineNumber":42,"columnNumber":4}]}},"redirectHasExtraInfo":false,"type":"Fetch","frameId":"0EAF2C6F51B54B385D52DC98E2FB76DB","hasUserGesture":false},"sessionId":"C2847CAF71AE4207E536EB03C654928E"}
CYPRESS-HAR-GENERATOR 71195: The plugin sends to the CDP: {"id":7,"method":"Network.getRequestPostData","params":{"requestId":"72375.67"}}
CYPRESS-HAR-GENERATOR 71195: Session C2847CAF71AE4207E536EB03C654928E associated with request: 72375.67
CYPRESS-HAR-GENERATOR 71195: The plugin receives from the CDP: {"id":7,"error":{"code":-32601,"message":"'Network.getRequestPostData' wasn't found"}}

Steps to reproduce

1. Modify a mock server defined in Send only necessary commands to retrieve the request post data #228

-app.get('/api/echo', (req: Request, res: Response) => res.json(req.body));
+app.post('/api/echo', raw(), (req: Request, res: Response) => res.text(req.body.toString()));

The index.hbs should be updated accordingly:

  <script>
-    const postData = {
-      document: document.body.innerHTML,
-    };
    const pre = document.querySelector('pre')
+    const blobContent = new XMLSerializer().serializeToString(document);

    fetch('/api/echo', {
      method: 'POST',
-      headers: { 'Content-Type': 'application/json' },
-      body: JSON.stringify(postData)
+      headers: { 'Content-Type': 'text/xml' },
+      body: new Blob([blobContent]) 
    })
-      .then(response => response.json())
-      .then(data => pre.innerText = JSON.stringify(data, null, 2))
+      .then(response => response.text())
+      .then(data => pre.innerText = data)
      .catch(error => console.error(error));
  </script>

2. Open a page and start recording using the following code:

cy.recordHar({ content: false });

cy.visit('/');

cy.saveHar({ waitForIdle: true });

Expected behavior
The HAR contains a postData for the request and is not affected by the type of BodyInit.