[1.10] Assert when opening upcoming project with custom ui modifications.

Verification Build: 1.10.0.0 Beta

Partner Rank: 4

Summary:
When opening an upcoming world that uses the ui .json files, there is an assert that happens a few times and then goes away.

Impact:

An assert.

Repro Steps:

1. Download the world uploaded in slack (#mco_everbloom) and open it with asserts enabled.

Observed Results: 

---------------------------
Assert Failure - ctrl+C to copy this message to the clipboard!
---------------------------
Assertion failed: unrecongized renderer: @ UIControlFactory::_populateCustomRenderComponent Function: in f:\darwinwork\6\s\handheld\src-client\common\client\gui\controls\uicontrolfactory.cpp @ 629

---------------------------
OK 
---------------------------

Expected Results: 
No assert

Screenshots/Videos attached: 

No