$extDisplay undefined; Can't add any Devices - causes SQL error (EndPoint Manager 2.10.3.2)

This appears to be a continuation of ticket FREEPBX-5483, http://www.freepbx.org/trac/ticket/5486.

When trying to add a device I get a lovely PHP error dump with the following in bold at the top:

{noformat}
FATAL SQL ERROR! ::::: SELECT * FROM endpointman_line_list WHERE ext = AND mac_id = 1 [nativecode=1064 ** You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND mac_id = 1' at line 1]SQL -{noformat}

Following the instructions in 5438 I updated to 2.10.2.4, in which the issue remained. I then pulled the latest bleeding edge available, 2.10.3.4, which also appears to have it. I'm marking this as major, if you'll forgive the impertinence, since it's a complete show-stopper on our system
- we have no way to add new devices right now.

I've attached the full spew dump of the output, just in case there's something important in there to add to this case.

Thank you muchly;

- Jock