### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Problem Description

We need to load a custom error page when the certificate is invalid but without "isMainFrame" property we don't know when to load the custom error page using webContents.loadURL()

### Proposed Solution

webContents.on("certificate-error", ((event, url, error, certificate, callback, isMainFrame)

### Alternatives Considered

Not sure

### Additional Information

Not sure
shell/browser/api/electron_api_app.cc
auto env = base::Environment::Create();
  if (env->HasVar("ELECTRON_FORCE_IS_PACKAGED"))
    return true;
  base::FilePath exe_path;
  base::PathService::Get(base::FILE_EXE, &exe_path);
  base::FilePath::StringType base_name =
      base::ToLowerASCII(exe_path.BaseName().value());
#if defined(OS_WIN)
  return base_name != FILE_PATH_LITERAL("electron.exe");
#else
  return base_name != FILE_PATH_LITERAL("electron");
#endif
}
base::FilePath App::GetPath(gin_helper::ErrorThrower thrower,