Support plan

• is this issue currently blocking your project? (yes/no): Yes
• is this issue affecting a production system? (yes/no): No

Context

• node version: v14.17.6
• module version with issue: v20.2.0
• last module version without issue:
• environment (e.g. node, browser, native): node + browser (via cypress)
• used with (e.g. hapi application, another framework, standalone, ...): "@hapi/inert": "6.0.4"
• any other relevant information:

What are you trying to achieve or the steps to reproduce?

I spent the whole day struggling with the flaky integration tests that were caused by unhandled promise rejection in Hapi sever when an incoming request is aborted.
The server crashes with

│ proc [kibana] TypeError: Cannot read property 'on' of null
   │ proc [kibana]     at Object.internals.chain (@hapi/hapi/lib/transmit.js:365:18)
   │ proc [kibana]     at Object.internals.transmit (@hapi/hapi/lib/transmit.js:120:30)
   │ proc [kibana]     at Object.exports.send (@hapi/hapi/lib/transmit.js:28:25)
   │ proc [kibana]     at Request._reply (@hapi/hapi/lib/request.js:459:9)

What I learned from the code inspection so far:

• Hapi receives an incoming request and calls a route handler
• the route handler responds with a JSON object
• Hapi started sending a request, https://github.com/hapijs/hapi/blob/master/lib/transmit.js#L28. Note that Hapi already checked the response in not failed! https://github.com/hapijs/hapi/blob/master/lib/transmit.js#L22-L24
• the incoming request is aborted
• Hapi overrides the response with Boom error Request aborted https://github.com/hapijs/hapi/blob/master/lib/request.js#L728
• server starts transmitting the original response containing the JSON object
• server crashes.

I guess it might happen because of a discrepancy between response and response.request.response content in transmit method https://github.com/hapijs/hapi/blob/master/lib/transmit.js#L28
I worked around the problem locally by adding the next snippet at the very top of transmit.

    if (response.request.response.isBoom) {
      await internals.fail(request, response.request.response);
      return;
    }

I don't think it's a proper fix but I don't know Hapi codebase to address the problem on my own so I'd appreciate any hints from the maintainers before I can open a PR.

Might be related to #4244 (comment) but the issue doesn't mention any problems with runtime errors.

What was the result you got?

Hapi crashes if an incoming request is aborted while the server is sending a response.

What result did you expect?

Hapi handles the abort event gracefully.