Minor code cleanup.

Signed-off-by: santorac <55155825+santorac@users.noreply.github.com>

Gems/Atom/RPI/Code/Include/Atom/RPI.Edit/Material/MaterialUtils.h

@@ -32,8 +32,7 @@ namespace AZ
             {
                 Empty,             //! No image was actually requested, the path was empty
                 Found,             //! The requested asset was found
-                Missing,           //! The requested asset was not found, and a placeholder asset was used instead
-                MissingNoFallback  //! The requested asset was not found, and a placeholder asset was not found either
+                Missing            //! The requested asset was not found, and a placeholder asset was used instead
             };
 
             //! Finds an ImageAsset referenced by a material file (or a placeholder)

Gems/Atom/RPI/Code/Source/RPI.Edit/Material/MaterialUtils.cpp

@@ -43,6 +43,11 @@ namespace AZ
                     
                     if (!imageAssetId.IsSuccess())
                     {
+                        // When the AssetId cannot be found, we don't want to outright fail, because the runtime has mechanisms for displaying fallback textures which gives the
+                        // user a better recovery workflow. On the other hand we can't just provide an empty/invalid Asset<ImageAsset> because that would be interpreted as simply
+                        // no value was present and result in using no texture, and this would amount to a silent failure.
+                        // So we use a randomly generated (well except for the "BADA55E7" bit ;) UUID which the runtime and tools will interpret as a missing asset and represent
+                        // it as such.
                         static const Uuid InvalidAssetPlaceholderId = "{BADA55E7-1A1D-4940-B655-9D08679BD62F}";
                         imageAsset = Data::Asset<ImageAsset>{InvalidAssetPlaceholderId, azrtti_typeid<StreamingImageAsset>(), imageFilePath};
                         return GetImageAssetResult::Missing;