Fatal error: Unexpectedly found nil while unwrapping an Optional value

[meroo36]

Describe the bug

App crashes after second time I initialize oauth2 flow in IOS.

To Reproduce

Steps to reproduce the behavior:

1. Click on a dynamic link to initialize the app with oauth flow
2. Authentication completes succesfully
3. Everthing works unless you click the dynamic link once more
4. You see the error: flutter_web_auth_2/SwiftFlutterWebAuth2Plugin.swift:29: Fatal error: Unexpectedly found nil while unwrapping an Optional value

Device (please complete the following information!)

• Device: Iphone 13
• OS: iOS 16.1.1
• flutter_web_auth_2 version: 2.2.1

[meroo36]

My guess is the sessionToKeepAlive variable is beeing nil for the second time.

var sessionToKeepAlive: Any? // if we do not keep the session alive, it will get closed immediately while showing the dialog
            completionHandler = { (url: URL?, err: Error?) in
                self.completionHandler = nil
                
                if #available(iOS 12, *) {
                    (sessionToKeepAlive as! ASWebAuthenticationSession).cancel() // Error Happens this line 29 in SwiftFlutterWebAuth2Plugin
                } else if #available(iOS 11, *) {
                    (sessionToKeepAlive as! SFAuthenticationSession).cancel()
                }
                
                sessionToKeepAlive = nil

EDIT: after commenting out the last line in the code block => "sessionToKeepAlive = nil". The issue seems to be gone.

@ThexXTURBOXx can you maybe give an hint why do we have to set it to nil and what would gone wrong if we dont set it to nil.

[meroo36]

I could fix the issue by wrapping the oauth2 call with a timer. I guess you need to wait a little untill the app is on the foreground succesfully.

        Timer(Duration(milliseconds: lazyLoginDelayTime), () async {
          List<String> scopes = ["*****", "******"];
          await account.createOAuth2Session(
              provider: "*******", scopes: scopes);
          await ref.read(authProvider.notifier).login();
        });

Closing for now.

[andreivarlamov]

Same issue, is it fixed in the 3.0.0?

[ThexXTURBOXx]

I think I have changed nothing in the Apple-specific implementations.
Also, I don't have any Apple hardware, so I cannot properly debug these issues. PRs are welcome, though.

[ozzy1873]

Here is a stack trace, perhaps it will help:

#0 (null) in Swift runtime failure: Unexpectedly found nil while unwrapping an Optional value ()

#1 0x000000010416d06c in closure #1 in SwiftFlutterWebAuth2Plugin.handle(_:result:) at /Users/xxx/.pub-cache/hosted/pub.dev/flutter_web_auth_2-2.2.1/ios/Classes/SwiftFlutterWebAuth2Plugin.swift:29

#2 0x000000010416cc08 in closure #1 in SwiftFlutterWebAuth2Plugin.handle(_:result:) at /Users/xxx/.pub-cache/hosted/pub.dev/flutter_web_auth_2-2.2.1/ios/Classes/SwiftFlutterWebAuth2Plugin.swift:29

#3 (null) in thunk for @escaping @callee_guaranteed (@in_guaranteed URL?, @guaranteed Error?) -> () ()

#4 (null) in -[ASWebAuthenticationSession _startDryRun:] ()

#5 0x000000010416ebb8 in specialized SwiftFlutterWebAuth2Plugin.handle(_:result:) at /Users/xxx/.pub-cache/hosted/pub.dev/flutter_web_auth_2-2.2.1/ios/Classes/SwiftFlutterWebAuth2Plugin.swift:100

#6 (null) in specialized SwiftFlutterWebAuth2Plugin.handle(_:result:) ()

#7 (null) in @objc SwiftFlutterWebAuth2Plugin.handle(_:result:) ()

[ThexXTURBOXx]

Thanks for the stacktrace. However, it sadly does not contain any additional information.
I have just released version 3.0.0-alpha.4.
It could contain a valid fix, but I don't have any Apple hardware to test this. So, please report back in case you tried it!
Also, if you are upgrading from 2.x, note the migration guide

[ThexXTURBOXx]

Will close for now until further feedback on 3.x