[Port] [6000.4] [UUM-131625] Fix subgraphs with only non-numeric outputs generating errors

Author: svc-reach-platform-support

Packages/com.unity.shadergraph/Editor/Data/SubGraph/SubGraphOutputNode.cs

@@ -27,6 +27,12 @@ class SubGraphOutputNode : AbstractMaterialNode
         };
         public bool IsFirstSlotValid = true;
 
+        // Returns true if the given slot is non-null and the slot's data may be used to render a preview
+        public static bool IsPreviewableType(MaterialSlot slot)
+        {
+            return slot == null ? false : s_ValidSlotTypes.Contains(slot.concreteValueType);
+        }
+
         public SubGraphOutputNode()
         {
             name = "Output";
@@ -75,7 +81,7 @@ void ValidateSlotType()
             {
                 owner.AddValidationError(objectId, s_MissingOutputSlot, ShaderCompilerMessageSeverity.Error);
             }
-            else if (!s_ValidSlotTypes.Contains(slots.FirstOrDefault().concreteValueType))
+            else if (!IsPreviewableType(slots.FirstOrDefault()))
             {
                 IsFirstSlotValid = false;
                 owner.AddValidationError(objectId, "Preview can only compile if the first output slot is a Vector, Matrix, or Boolean type. Please adjust slot types.", ShaderCompilerMessageSeverity.Error);

Packages/com.unity.shadergraph/Editor/Generation/Processors/GenerationUtils.cs

@@ -1040,7 +1040,7 @@ internal static void GenerateSurfaceDescriptionStruct(ShaderStringBuilder surfac
                     if (isSubgraphOutput)
                     {
                         var firstSlot = slots.FirstOrDefault();
-                        if (firstSlot != null)
+                        if (SubGraphOutputNode.IsPreviewableType(firstSlot))
                         {
                             var hlslName = $"{NodeUtils.GetHLSLSafeName(firstSlot.shaderOutputName)}_{firstSlot.id}";
                             surfaceDescriptionStruct.AppendLine("{0} {1};", firstSlot.concreteValueType.ToShaderString(firstSlot.owner.concretePrecision), hlslName);
@@ -1206,7 +1206,7 @@ static void GenerateSurfaceDescriptionRemap(
             else if (rootNode is SubGraphOutputNode)
             {
                 var slot = slots.FirstOrDefault();
-                if (slot != null)
+                if (SubGraphOutputNode.IsPreviewableType(slot))
                 {
                     var foundEdges = graph.GetEdges(slot.slotReference).ToArray();
                     var hlslName = $"{NodeUtils.GetHLSLSafeName(slot.shaderOutputName)}_{slot.id}";