Lobby Error Help

I am taking the lobby starter project and adding my own scene to it by assigning it to the lobby manager in the editor.

After doing so, and running the project, I get the two errors below.
NOTE: The error occurs WHEN THE LOBBY UI IS DISPLAYED, before it even attempts to load the scene.

Further, even if I restore the original scene on the lobby manager, the error keeps occurring.
It APPEARS non-destructive, but there should be no error whatsoever.

Help Mr. Wizard!

****** ERROR 1 *************
Uncaught exception in async net callback: Object reference not set to an instance of an object
UnityEditor.AsyncHTTPClient:Done(State, Int32)

****** ERROR 2 *************
at UnityEngine.GUISkin.GetStyle (System.String styleName) [0x00010] in C:\buildslave\unity\build\Runtime\IMGUI\Managed\GUISkin.cs:312
at UnityEngine.GUIStyle.op_Implicit (System.String str) [0x00020] in C:\buildslave\unity\build\Runtime\IMGUI\Managed\GUIStyle.cs:566
at UnityEditor.ProjectBrowser.InitSearchMenu () [0x00014] in C:\buildslave\unity\build\Editor\Mono\ProjectBrowser.cs:483
at UnityEditor.ProjectBrowser.AssetStoreSearchEndedCallback () [0x00000] in C:\buildslave\unity\build\Editor\Mono\ProjectBrowser.cs:511
at UnityEditor.ObjectListArea+c__AnonStorey3A.<>m__50 (UnityEditor.AssetStoreSearchResults results) [0x00356] in C:\buildslave\unity\build\Editor\Mono\ObjectListArea.cs:406
at UnityEditor.AssetStoreResultBase`1[Derived].Parse (UnityEditor.AssetStoreResponse response) [0x000fc] in C:\buildslave\unity\build\Editor\Mono\AssetStore\AssetStoreClient.cs:89
at UnityEditor.AssetStoreClient+c__AnonStorey53.<>m__91 (UnityEditor.AssetStoreResponse ar) [0x00000] in C:\buildslave\unity\build\Editor\Mono\AssetStore\AssetStoreClient.cs:751
at UnityEditor.AssetStoreClient+c__AnonStorey52.<>m__8F (UnityEditor.AsyncHTTPClient job) [0x00012] in C:\buildslave\unity\build\Editor\Mono\AssetStore\AssetStoreClient.cs:624
UnityEditor.AsyncHTTPClient:Done(State, Int32)

This just happened to me too!

By mistake I deleted “Checker.mat” and “Checker.png” files from my Probuilder/…/ folder. Removing Probuilder folder completely and reinstalling Probuilder fixed the issue.