UMG Crashes When Using "Create Dynamic Material Instance" With An Optional Name Twice

When using an Optional Name parameter in Create Dynamic Material Instance while using the same Optional Name twice in UMG the engine crashes.

I have tested this in a actor blueprint that applies the texture to a cube mesh and their isn't a crash.

Found in 4.24.2 CL#11100242
Reproduced in 4.23.1 CL#9631420, 4.26 Main CL#11421855

1. Create a UI Widget (DemoWidget).
2. Add a button and an image to DemoWidget.
3. Create a new material an set Material Domain to "User Interface".
4. In DemoWidget add an On Clicked for the button that calles "Create Dynamic Material Instance" using an optional name.
5. Assign the image in DemoWidget the material made in step 4 using "Set Brush from Material".
6. In the level blueprint create a DemoWidget and add it to the viewport.
7. Play the scene and click the button twice.

Result: Engine crashes.

Expected: Engine doesn't crash.

LoginId:9a8d08644d702ac44f074090ac311686
EpicAccountId:580fb2844ad145d79dff08f42acea7c6

Assertion failed: MaterialObjectWeakPtr.IsValid(bEvenIfPendingKill, bThreadSafe) [Link Removed] [Line: 101] Material UiMaterial has become invalid. This means the resource was garbage collected while slate was using it

UE4Editor_Core!AssertFailedImplV() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:105]
UE4Editor_Core!FDebug::CheckVerifyFailedImpl() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:455]
UE4Editor_SlateRHIRenderer!DispatchCheckVerify<void,<lambda_a21d876fe726a83b877fc869f570fe39> >() [d:\build\++ue4\sync\engine\source\runtime\core\public\misc\assertionmacros.h:167]
UE4Editor_SlateRHIRenderer!FSlateMaterialResource::CheckForStaleResources() [d:\build\++ue4\sync\engine\source\runtime\slaterhirenderer\private\slatematerialresource.cpp:101]
UE4Editor_SlateRHIRenderer!FSlateRHIRenderingPolicy::DrawElements() [d:\build\++ue4\sync\engine\source\runtime\slaterhirenderer\private\slaterhirenderingpolicy.cpp:1025]
UE4Editor_SlateRHIRenderer!FSlateRHIRenderer::DrawWindow_RenderThread() [d:\build\++ue4\sync\engine\source\runtime\slaterhirenderer\private\slaterhirenderer.cpp:871]
UE4Editor_SlateRHIRenderer!TEnqueueUniqueRenderCommandType<`FSlateRHIRenderer::DrawWindows_Private'::`26'::SlateDrawWindowsCommandName,<lambda_2a9c0a9fed59e8507bcd2f8c06e1febe> >::DoTask() [d:\build\++ue4\sync\engine\source\runtime\rendercore\public\renderingthread.h:198]
UE4Editor_SlateRHIRenderer!TGraphTask<TEnqueueUniqueRenderCommandType<`FSlateRHIRenderer::DrawWindows_Private'::`26'::SlateDrawWindowsCommandName,<lambda_2a9c0a9fed59e8507bcd2f8c06e1febe> > >::ExecuteTask() [d:\build\++ue4\sync\engine\source\runtime\core\public\async\taskgraphinterfaces.h:847]
UE4Editor_Core!FNamedTaskThread::ProcessTasksNamedThread() [d:\build\++ue4\sync\engine\source\runtime\core\private\async\taskgraph.cpp:686]
UE4Editor_Core!FNamedTaskThread::ProcessTasksUntilQuit() [d:\build\++ue4\sync\engine\source\runtime\core\private\async\taskgraph.cpp:583]
UE4Editor_RenderCore!RenderingThreadMain() [d:\build\++ue4\sync\engine\source\runtime\rendercore\private\renderingthread.cpp:340]
UE4Editor_RenderCore!FRenderingThread::Run() [d:\build\++ue4\sync\engine\source\runtime\rendercore\private\renderingthread.cpp:471]
UE4Editor_Core!FRunnableThreadWin::Run() [d:\build\++ue4\sync\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:96]