Backports #1543 to v11

Fixes #1540 :

When the server returns an error code with JSON body, and I try to parse it using .json() and {throwHttpErrors: false}, I get the following error:

TypeError: Cannot read property 'request' of undefined
    at /path/to/my/project/node_modules/got/dist/source/as-promise/index.js:157:48
    at processTicksAndRejections (internal/process/task_queues.js:93:5)

Checklist

• I have read the documentation.
• I have included a pull request description of my changes.
• I have included some tests.
• If it's a new feature, I have included documentation updates in both the README and the types.