GitHub Copilot App 1.1.9 crashes on startup with "Invalid regular expression: invalid group specifier name"

[allytjohnson]

Description

GitHub Copilot App version 1.1.9 fails to start on macOS with a SyntaxError related to an invalid regular expression. The application shows an error dialog immediately after launch and never reaches an interactive state.

Error Details

SyntaxError: Invalid regular expression: invalid group specifier name
parseModule@[native code]
@[native code]
asyncFunctionResume@[native code]
@[native code]
promiseReactionJobWithoutPromise@[native code]
promiseReactionJob@[native code]

Steps to Reproduce

1. Download GitHub Copilot App version 1.1.9 from the official releases page
2. Install the application to /Applications/GitHub Copilot.app
3. Open the GitHub Copilot application
4. Attempt to authenticate with GitHub account

Expected Behavior

The application should launch successfully and present the authentication/login screen.

Actual Behavior

The application displays an error dialog: "GitHub Copilot could not start - GitHub Copilot could not finish loading." with the SyntaxError shown above. The application then becomes unresponsive.

Environment

• macOS Version: Monterey or later (x86_64)
• GitHub Copilot App Version: 1.1.9
• Platform: macOS (x86_64)
• Build: Release (build_debug=false)
• Commit: 07245f4

Log Output

The application logs show the frontend failing before becoming interactive:

2026-08-14T19:23:49.537901Z ERROR github_app: Frontend failed before becoming interactive event="frontend.startup_failed" window="main" details=SyntaxError: Invalid regular expression: invalid group specifier name
parseModule@[native code]
@[native code]
asyncFunctionResume@[native code]
@[native code]
promiseReactionJobWithoutPromise@[native code]
promiseReactionJob@[native code]

Full log file: /Users/alexandriajohnson/.copilot/logs/github-app.56053.log

Troubleshooting Attempted

• Restarted the application
• Cleared application cache and data (~/.copilot/)
• Removed and reinstalled the application completely
• Verified download integrity from official GitHub releases page
• Attempted fresh installation after clearing system cache

Additional Context

This appears to be a regression in version 1.1.9, as 1.1.9 is the only available version and there is no option to downgrade to previous versions for testing. The error occurs consistently across clean installations with no other extensions or modifications interfering.

The error suggests a malformed regular expression in the bundled frontend JavaScript code, specifically during the module parsing phase at startup.