Fix: missing return in handle_get_credentials

[mattmundell]

What

In the GET_CREDENTIALS handler, add a return after the credential format error.

Why

The return is required else gvmd sends the credentials after the error response.

This format error can be invoked by calling GET_CREDENTIALS with an erroneous format attribute, for example:

$ o m m '<get_credentials format="err" filter="rows=1 sort=name"/>'

Here's the response before the PR (note the extra get_credentials_response element):

<get_credentials_response status="400" status_text="Format attribute should be 'key', 'rpm', 'deb', 'exe' or 'pem'" />
<get_credentials_response status="200" status_text="OK">
  <credential id="c1e69303-bd6b-4c02-860b-8c41f34064f4">
  ...

Here's the response after the PR, with the single correct element:

<get_credentials_response status="400"
status_text="Format attribute should be 'key', 'rpm', 'deb', 'exe' or 'pem'" />```

[github-actions]

Conventional Commits Report

Type	Number
Bug Fixes	1

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