LDAP group link select dropdown error

In 9.3, the LDAP group link select dropdown is broken. I see in the development log that the actual LDAP query comes back correctly, but the JS console shows errors and no results are ever displayed.

The error in the JS console is:

Screen_Shot_2017-06-27_at_10.14.13_AM

cc/ @jschatz1 @timzallmann Can you please help us debug this quickly? It's a big feature for EE.