Fix CA2200, don't rethrow exceptions

Author: bpulliam

Samples/SceneGraph/Demos/MaterialCreator/MaterialCreatorApp/Model/Layers/ImageLayer.cs

@@ -126,7 +126,7 @@ private async Task<StorageFile> LoadFromFilePath(string filePath)
                 }
                 else
                 {
-                    throw e;
+                    throw;
                 }
             }
         }