Notice: Undefined index: #language in conditional_fields_get_selector()

Problem/Motivation

When configuring a condition and you choose to have a custom jQuery selector as control field inside the conditional_fields_get_selector() function there is replace for the %lang with the current language of the $dependee_form_field.
If the language attribute is not present a notice is triggered.

Proposed resolution

I suggest to have a check for the existence of the language attribute, if not replace it with the current_language id.