Issuer.discover is returning a spread string

Describe the bug The request call inside the Issuer.discover method is returning a string instead of the object, which in turn is getting spread by the spread operator.

code from issuer.js

 const response = await request.call(this, {
          method: 'GET',
          responseType: 'json',
          url: wellKnownUri,
        });
        const body = processResponse(response);

The body is coming as string instead of object as expected. Which is then getting spread in the below code, hence the bug.

return new Issuer({
          ...ISSUER_DEFAULTS,
          ...body,
          [AAD_MULTITENANT]: !!AAD_MULTITENANT_DISCOVERY.find(
            (discoveryURL) => wellKnownUri.startsWith(discoveryURL),
          ),
        });

To Reproduce Well Known Configuration link generated by the openid-client package: https://login.microsoftonline.com/18a59a81-eea8-4c30-948a-d8824cdc2580/v2.0/.well-known/openid-configuration Issuer and Client configuration: (inline or gist) - Don’t forget to redact your secrets.

Issuer is constructed by discovery.


Steps to reproduce the behaviour:

1.  call `Issuer.discover` method and pass the issuer url. 
`Issuer.discover('https://login.microsoftonline.com/18a59a81-eea8-4c30-948a-d8824cdc2580/v2.0')`

**Expected behaviour**
`Issuer.discover` returns an object containing Issuer and it's metadata.

**Environment:**
 - openid-client version: [e.g. v4.7.4]
 - node version: [e.g. v12.16.2]

**Additional context**
Add any other context about the problem here.

 - [x] the bug is happening on latest openid-client too.
 - [x] i have searched the issues tracker on github for similar issues and couldn't find anything related.

[panva]

@ktikku I can reproduce the issue, but it seems to be related to a node.js version, not the library. Upgrading to latest v14 (v14.16.0) the issue is gone.

Also note that the engines version actually covers this problem as the minimum v14 is 14.2.0. It must’ve been a known issue I just don’t remember.

"node": "^10.19.0 || >=12.0.0 < 13 || >=13.7.0 < 14 || >= 14.2.0"

[ktikku]

ya, just checked, it’s working fine now with node 14.2.0. Thanks for the assistance @panva 😄