[UUM-126022] Fix the Screen Space Overlay UI rendering in URP when creating cameras at runtime without UniversalAdditionalCameraData.

Author: mseonkim-unity

Packages/com.unity.render-pipelines.universal/Runtime/UniversalRenderPipelineCore.cs

@@ -1492,8 +1492,9 @@ private int GetLastBaseCameraIndex(List<Camera> cameras)
             int lastBaseCameraIndex = 0;
             for (int i = 0; i < cameras.Count; i++)
             {
+                // Assume a camera is a base camera if no UniversalAdditionalCameraData is available (e.g., for cameras created at runtime).
                 cameras[i].TryGetComponent<UniversalAdditionalCameraData>(out var baseCameraAdditionalData);
-                if (baseCameraAdditionalData?.renderType == CameraRenderType.Base)
+                if (baseCameraAdditionalData == null || baseCameraAdditionalData.renderType == CameraRenderType.Base)
                     lastBaseCameraIndex = i;
             }
             return lastBaseCameraIndex;