For use with dispatchSubsection. Calls your filter with the request and if your filter returns false, this issues the given errorCode and stops processing.

bool hasAdminPermissions(Cgi cgi) {
	return true;
}

mixin DispatcherMain!(
	"/admin".dispatchSubsection!(
		passFilterOrIssueError!(hasAdminPermissions, 403),
		KeepExistingPresenter,
		"/".serveApi!AdminFunctions
	)
);