Not authorized to send Apple events to Mail

I have a simple Swift-based macOS app that creates and executes an Apple Script:

let unreadEmailsScript = """
                             tell application "Mail"
                                  get unread count of inbox
                             end tell
                             """
    if let scriptObject = NSAppleScript(source: unreadEmailsScript) {
      var errorDict: NSDictionary? = nil
      scriptObject.executeAndReturnError(&errorDict)
     
      if let error = errorDict {
          print(error)
      }
    }

I've added the following to my project's entitlements:

<key>com.apple.security.temporary-exception.apple-events</key>

<array>

<string>com.apple.Mail</string>

</array>

When I execute this on the latest version (18A389) of Mojave the code prints:

{
    NSAppleScriptErrorAppName = Mail;
    NSAppleScriptErrorBriefMessage = "Not authorized to send Apple events to Mail.";
    NSAppleScriptErrorMessage = "Not authorized to send Apple events to Mail.";
    NSAppleScriptErrorNumber = "-1743";
    NSAppleScriptErrorRange = "NSRange: {33, 12}";
}

The system doesn't prompt me for authorization at app launch.

What is the correct way to send Apple Events to Mail via a Swift app under Mojave?

TIA