fix(nvd_source): fix configuration without nodes

[ffontaine]

https://nvd.nist.gov/vuln/detail/cve-2025-40939 has the following configurations: [{}]

This will result in a crash as current code wrongly assumes that all configuration object has a nodes parameter

[ffontaine]

One of the test fails on:

Downloading Chromium 143.0.7499.4 (playwright build v1200) from https://playwright.download.prss.microsoft.com/dbazure/download/playwright/builds/chromium/1200/chromium-linux.zip
(node:3746) [DEP0169] DeprecationWarning: `url.parse()` behavior is not standardized and prone to errors that have security implications. Use the WHATWG URL API instead. CVEs are not issued for `url.parse()` vulnerabilities.
(Use `node --trace-deprecation ...` to show where the warning was created)
Error: connect ECONNREFUSED 54.185.253.63:443
    at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1637:16) {
  errno: -111,
  code: 'ECONNREFUSED',
  syscall: 'connect',
  address: '54.185.253.63',
  port: 443
}
Failed to install browsers
Error: Failed to download Chromium 143.0.7499.4 (playwright build v1200), caused by
Error: Download failure, code=1
    at ChildProcess.<anonymous> (/opt/hostedtoolcache/Python/3.13.11/x64/lib/python3.13/site-packages/playwright/driver/package/lib/server/registry/browserFetcher.js:94:32)
    at ChildProcess.emit (node:events:508:28)
    at ChildProcess._handle.onexit (node:internal/child_process:294:12)

https://playwright.download.prss.microsoft.com/dbazure/download/playwright/builds/chromium/1200/chromium-linux.zip is perfectly reachable from my local machine.
Connection refused is returned by 54.185.253.63 which is associated to ec2-54-185-253-63.us-west-2.compute.amazonaws.com.
So, I don't know what is going on, @terriko do you have an idea?