public async Task OnGetAsync(string returnUrl = null)
{
if (!string.IsNullOrEmpty(ErrorMessage))
{
ModelState.AddModelError(string.Empty, ErrorMessage);
}
returnUrl = returnUrl ?? Url.Content("~/");
// Clear the existing external cookie to ensure a clean login process
await HttpContext.SignOutAsync(IdentityConstants.ExternalScheme);
ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList();
ReturnUrl = returnUrl ?? Url.Content("~/");
TempData["ReturnUrl"] = ReturnUrl;
}
