fix: support node 22 xhr compatibility

[fatso83]

Attempt at finishing #218

Summary

• separate fake XHR Blob and FormData handling from bare global assumptions so Node 22+ works when FileReader or FormData are absent in a given context
• update blob response assertions to use Blob.text() and align support declarations/CI with Node 22+
• fix stale unsafeHeadersEnabled tests to use nise's fake server/XHR fixtures instead of removed sinon.fakeServer APIs

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	@​sinonjs/​fake-timers@​15.1.0 ⏵ 15.1.1				+6

View full report

[fatso83]

the change is specifically about not assuming those APIs always exist together.

What the PR actually changes:

• In lib/fake-xhr/index.js, FormData is now looked up at runtime through the global object before doing instanceof checks. That means:
  • if FormData exists, send(formData) still behaves as FormData;
  • if FormData does not exist in that runtime/context, nise no longer throws a ReferenceError.
• In lib/fake-xhr/blob.js and lib/fake-xhr/index.js, blob support is based on Blob, not FileReader. That means blob responses still work when
  Blob exists even if FileReader does not.
• In lib/fake-xhr/index.test.js, blob assertions were changed from FileReader to Blob.text(). That is a test adaptation to modern Node, but it
  matches the production behavior change above rather than papering over it.

What it does not do:

• It does not polyfill FormData.
• It does not polyfill FileReader.
• It does not guarantee support for code paths that truly require FileReader in an environment where FileReader is absent.

In short, the PR preserves FormData behavior when FormData exists, preserves blob behavior when Blob exists, and removes the incorrect dependency on FileReader for blob support. It is not “adding FileReader support”; it is removing the false assumption that FileReader must exist for blob responses to work.