fix: crash when no response mediaType

[donocode]

Status

READY

Description

Our use of orval started to break because a response like:

ok:
  description: Return file location
  headers:
    Location:
      description: Temporary URI where the file can be found
      schema:
        type: string
        format: uri

appeared in our openapi file. I was able to track it to this attempt to use a possibly undefined object

Related PRs

N/A

Todos

• Tests
• Documentation
• Changelog Entry (unreleased)

Steps to Test or Reproduce

Outline the steps to test or reproduce the PR here.

> git pull --prune
> git checkout <branch>
> grunt jasmine