[ShaderGraph][Universal] Fix an NRE for URP sub-datas.

Added some null checks for SG serialization objects used by Universal Target.

Also cleaned up the error messaging, which isn't useful or actionable to users in this circumstance.

Author: Esmeralda Salamone

Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Targets/UniversalTarget.cs

@@ -694,6 +694,9 @@ void ClearUnusedData()
             for (int i = 0; i < m_Datas.Count; i++)
             {
                 var data = m_Datas[i];
+                if (data.value is null)
+                    continue;
+
                 var type = data.value.GetType();
 
                 // Data requirement interfaces need generic type arguments
@@ -710,7 +713,17 @@ public void SetDataOnSubTarget<T>(SubTarget subTarget) where T : JsonObject
                 return;
 
             // Ensure data object exists in list
-            var data = m_Datas.SelectValue().FirstOrDefault(x => x.GetType().Equals(typeof(T))) as T;
+
+            T data = null;
+            foreach (var x in m_Datas.SelectValue())
+            {
+                if (x.GetType().Equals(typeof(T)))
+                {
+                    data = x as T;
+                    continue;
+                }
+            }
+
             if (data == null)
             {
                 data = Activator.CreateInstance(typeof(T)) as T;

Packages/com.unity.shadergraph/Editor/Resources/Styles/HelpBoxRow.uss

@@ -36,7 +36,6 @@ HelpBoxRow
 
 .help-box-row-style-warning
 {
-    background-color: #fcd76e;
 }
 
 .help-box-row-style-warning #label
@@ -46,7 +45,6 @@ HelpBoxRow
 
 .help-box-row-style-error
 {
-    background-color: #fc6e6e;
 }
 
 .help-box-row-style-error #label

Packages/com.unity.shadergraph/Editor/Serialization/JsonData.cs

@@ -39,7 +39,6 @@ public void OnAfterDeserialize()
                     }
                     else
                     {
-                        Debug.LogError($"Missing {typeof(T).FullName} {m_Id}");
                     }
                 }
                 catch (Exception e)