Improve error message if user signs in with Apple ID that isn't a developer

[interstateone]

Not sure of the details of this yet, but had a user that was running xcodes update, signing in successfully, then got this error output:

The operation couldn't be completed. (DecodingError.keyNotFound(CodingKeys(stringValue: "downloads", intValue: nil), Swift.DecodingError.Context(codingPath: [], debugDescription: "No value associated with key CodingKeys(stringValue: \"downloads\", intValue: nil) (\"downloads\").", underlyingError: nil)))

The error message seems to indicate that parsing the downloads JSON failed because the session was invalid.

It turns out their Apple ID wasn't a developer account. Need to investigate if this means "doesn't have a valid ADC membership" or something else.

[MattKiazyk]

@interstateone I believe this happens too when you type in the 2FA code wrong. Just got

The operation couldn’t be completed. (DecodingError.keyNotFound(CodingKeys(stringValue: "downloads", intValue: nil), Swift.DecodingError.Context(codingPath: [], debugDescription: "No value associated with key CodingKeys(stringValue: \"downloads\", intValue: nil) (\"downloads\").", underlyingError: nil)))

[interstateone]

Interesting, I thought that was already handled better. Thanks for calling it out, could you open a new issue to track it?

[interstateone]

Confirmed the response with a new test Apple ID. Fetching the seedlist with a user that isn't registered as a developer returns:

HTTP/1.1 200 OK
Server: Apple
Date: Thu, 01 Oct 2020 03:02:39 GMT
Content-Type: text/plain;charset=iso-8859-1
Content-Length: 127
Cache-Control: no-store, no-cache, must-revalidate
Pragma: no-cache
X-XSS-Protection: 1; mode=block
Host: developer.apple.com
X-Frame-Options: SAMEORIGIN
rqId: 13024554367ea1b57bc6850125677e25
Age: 0
Via: https/1.1 usscz2-edge-lx-008.ts.apple.com (ApacheTrafficServer/8.1.0), https/1.1 usscz2-edge-bx-005.ts.apple.com (ApacheTrafficServer/8.1.0)
CDNUUID: 8e2ac702-18c9-4aaf-94a3-cc0253b9c5a4-586545440
X-Cache: miss, miss
Connection: close

{
  "responseId": "55e8d7fc-3e14-401f-bdf1-db96649fe523",
  "resultCode": 2100,
  "resultString": "You are not registered as an Apple Developer.  Please visit Apple Developer Registration. https://developer.apple.com/register/",
  "userString": "You are not registered as an Apple Developer.  Please visit Apple Developer Registration. https://developer.apple.com/register/",
  "creationTimestamp": "2020-10-01T03:23:00Z",
  "protocolVersion": "QH65B2",
  "userLocale": "en_US",
  "requestUrl": "https://developer.apple.com/services-account/QH65B2/downloadws/listDownloads.action",
  "httpCode": 200
}

We should print out the response body in this case.

[MattKiazyk]

closing as of 1.0 we now no longer require apple accounts to download xcode