Merge pull request #304 from aws-lumberyard-dev/Atom/santorac/ShaderCollectionItemFixMain-LYN-2905

Cherrypicked the fix from the 1.0 branch to main (see #301).

Added a check for m_shaderAsset.IsReady() before trying to use the asset data. Also added a check before calling BlockUntilLoadComplete() to prevent reporting an error message unnecessarily.

Set the reflection name for ShaderCollection::Item to "ShaderCollectionItem" so it doesn't show up as just "Item" in Script Canvas.

Gems/Atom/RPI/Code/Source/RPI.Reflect/Material/ShaderCollection.cpp

@@ -40,13 +40,22 @@ namespace AZ
                 // Dependent asset references aren't guaranteed to finish loading by the time this asset is serialized, only by
                 // the time this asset load is completed.  But since the data is needed here, we will deliberately block until the
                 // shader asset has finished loading.
-                shaderVariantReference->m_shaderAsset.QueueLoad();
-                shaderVariantReference->m_shaderAsset.BlockUntilLoadComplete();
-
-                shaderVariantReference->m_shaderOptionGroup = ShaderOptionGroup{
-                    shaderVariantReference->m_shaderAsset->GetShaderOptionGroupLayout(),
-                    shaderVariantReference->m_shaderVariantId
-                };
+                if (shaderVariantReference->m_shaderAsset.QueueLoad())
+                {
+                    shaderVariantReference->m_shaderAsset.BlockUntilLoadComplete();
+                }
+
+                if (shaderVariantReference->m_shaderAsset.IsReady())
+                {
+                    shaderVariantReference->m_shaderOptionGroup = ShaderOptionGroup{
+                        shaderVariantReference->m_shaderAsset->GetShaderOptionGroupLayout(),
+                        shaderVariantReference->m_shaderVariantId
+                    };
+                }
+                else
+                {
+                    shaderVariantReference->m_shaderOptionGroup = {};
+                }
             }
         };
 
@@ -82,7 +91,7 @@ namespace AZ
 
             if (BehaviorContext* behaviorContext = azrtti_cast<BehaviorContext*>(context))
             {
-                behaviorContext->Class<Item>()
+                behaviorContext->Class<Item>("ShaderCollectionItem")
                     ->Attribute(AZ::Script::Attributes::Scope, AZ::Script::Attributes::ScopeFlags::Automation)
                     ->Attribute(AZ::Script::Attributes::Category, "Shader")
                     ->Attribute(AZ::Script::Attributes::Module, "shader")