Problem with filtering User by role in client script


i am struggeling with filtering User objects in a Link field by role.
In my Client script (js file of the form) i use the following sequence:

    frm.set_query("monteur2", function() {
        // Hier auf role_profile_name oder role_profiles prüfen
        return {
            filters: [
                ["User", "user_type", "=", "System User"],
                ["User", "enabled", "=", 1],
                ["Has Role", "role", "=", "MDS-Monteur"],

I get the following error

“exception”: “AttributeError: ‘list’ object has no attribute ‘get’”,
“exc_type”: “AttributeError”

Has anyone an idea how to solve the problem.
Someone said, this could be a bug in the User object of frappe.