Assistant: Broken state of dialog for adding GitHub Copilot provider if user cancels

[rodrigosf672]

System details: macOS Sequoia 15.4.1

Positron and OS details:

Positron Version: 2025.06.0 (Universal) build 70 Code - OSS Version: 1.99.0 Commit: 781a718f3c9eb40dc95137bbb5a9fc4d8c221bdc Date: 2025-05-15T03:33:17.998Z Electron: 34.3.2 Chromium: 132.0.6834.210 Node.js: 20.18.3 V8: 13.2.152.41-electron.0 OS: Darwin arm64 24.4.0

Interpreter details:

Python 3.11.12

Describe the issue:

When user tries to cancel addition of GitHub Copilot (Language Model Provider), dialog gets into a broken state

Steps to reproduce the issue:

1. Add a new Language Model.
2. Select GitHub Copilot --> Sign in --> Ok (Positron dialog) --> Open (System dialog) --> Close open browser window --> Dialog in broken state (i.e., loading forever)

Expected or desired behavior:

User is able to close the authentication dialog without leading dialog to get into a broken state. Following (or similar) message should be displayed.

[rodrigosf672]

Please note that this is a different issue from #7617. In this issue herein reported, dialog gets into a broken state, forever loading, due to user closing the authentication window (browser). In the other issue, Positron ignores cancellation of dialog, still opening the browser window. Logging them separately. cc @testlabauto @jonvanausdeln

[testlabauto]

Rodrigo, could we get a fullpage screenshot?

[jonvanausdeln]

Verified Fixed

Positron Version(s) : 2025.07.0-49 OS Version(s) : Windows 11

Test scenario(s)

Using original repro steps, you can now cancel out of the flow. Using the new cancel button.