- Avoid add null shaderChunks

- Public for normal slot (useful for default input)

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/WorldSpaceNormalNode.cs

     [Title("Input/World Normal Node")]
     public class WorldSpaceNormalNode : AbstractMaterialNode, IMayRequireNormal
     {
-        private const int kOutputSlotId = 0;
-        private const string kOutputSlotName = "Normal";
+        public const int kOutputSlotId = 0;
+        public const string kOutputSlotName = "Normal";
 
         public WorldSpaceNormalNode()
         {

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Util/ShaderGenerator.cs

 
         public void AddShaderChunk(string s, bool unique)
         {
+            if (string.IsNullOrEmpty(s))
+                return;
+
             if (unique && m_ShaderChunks.Any(x => x.chunkString == s))
                 return;