electron: Stream protocols and fs.createReadStream sometimes never complete in Electron 7

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for an issue that matches the one I want to file, without success.

Issue Details

• Electron Version:
  • 7.0.0-beta.4 - 8.0.0-beta.2
• Operating System:
  • macOS 10.14.6, Windows 10
• Last Known Working Electron version:
  • 7.0.0-beta.3

Expected Behavior

According to the docs, one should be able to register a stream protocol handler which serves files from the file system.

The following code snippet is suggested by the docs:

const { protocol } = require('electron')
const fs = require('fs')

protocol.registerStreamProtocol('atom', (request, callback) => {
  callback(fs.createReadStream('index.html'))
}, (error) => {
  if (error) console.error('Failed to register protocol')
})

The expected behavior is that Electron should read from the stream and (assuming no read errors etc.) serve a valid response for the custom protocol request.

Actual Behavior

Starting with Electron 7.0.0-beta.4 it looks like the request sometimes randomly never completes on the Renderer side. This can be seen in the Network tab as well as by inspecting AJAX calls at runtime. The read stream seems to be created successfully, and the response starts to be sent back to the renderer, but the final state change never happens.

To Reproduce

Run the following Fiddle to see the behavior change. In Electron < 7.0.0-beta4, the page can make an AJAX request to the custom scheme in a loop and print the contents. In Electron >= 7.0.0-beta4 the page can occasionally make a few AJAX requests, but it will eventually halt when one request never reaches a XMLHttpRequest.DONE state.

https://gist.github.com/33a9b357c606c7cbe7c2cac99bbda973

Good console output (7.0.0-beta3 and bellow) looks like:

index.html:22 ajaxStateChange readyState: 1 statusCode: 0
index.html:22 ajaxStateChange readyState: 2 statusCode: 200
index.html:22 ajaxStateChange readyState: 3 statusCode: 200
index.html:22 ajaxStateChange readyState: 4 statusCode: 200
index.html:25 // Just using this file as an example file to be served by the custom scheme handler
index.html:22 ajaxStateChange readyState: 1 statusCode: 0
index.html:22 ajaxStateChange readyState: 2 statusCode: 200
index.html:22 ajaxStateChange readyState: 3 statusCode: 200
index.html:22 ajaxStateChange readyState: 4 statusCode: 200
index.html:25 // Just using this file as an example file to be served by the custom scheme handler
index.html:22 ajaxStateChange readyState: 1 statusCode: 0
index.html:22 ajaxStateChange readyState: 2 statusCode: 200
index.html:22 ajaxStateChange readyState: 3 statusCode: 200
index.html:22 ajaxStateChange readyState: 4 statusCode: 200
index.html:25 // Just using this file as an example file to be served by the custom scheme handler
... and repeat

Bad console output (7.0.0-beta4+) looks like:

index.html:22 ajaxStateChange readyState: 1 statusCode: 0
index.html:22 ajaxStateChange readyState: 2 statusCode: 200
index.html:22 ajaxStateChange readyState: 3 statusCode: 200
index.html:22 ajaxStateChange readyState: 4 statusCode: 200
index.html:25 // Just using this file as an example file to be served by the custom scheme handler
index.html:22 ajaxStateChange readyState: 1 statusCode: 0
index.html:22 ajaxStateChange readyState: 2 statusCode: 200
index.html:22 ajaxStateChange readyState: 3 statusCode: 200
index.html:22 ajaxStateChange readyState: 4 statusCode: 200
index.html:25 // Just using this file as an example file to be served by the custom scheme handler
index.html:22 ajaxStateChange readyState: 1 statusCode: 0
index.html:22 ajaxStateChange readyState: 2 statusCode: 200
index.html:22 ajaxStateChange readyState: 3 statusCode: 200  <-- stop getting updates here

Screenshots

Network info for request that completes successfully:

Network info for request that never completes:

Additional Information