Fix extensionless image loading panic (#13005)

Remake of #12938 targeting main

Author: victoryaskevich

crates/bevy_render/src/texture/image_loader.rs

@@ -91,13 +91,14 @@ impl AssetLoader for ImageLoader {
         settings: &'a ImageLoaderSettings,
         load_context: &'a mut LoadContext<'_>,
     ) -> Result<Image, Self::Error> {
-        // use the file extension for the image type
-        let ext = load_context.path().extension().unwrap().to_str().unwrap();
-
         let mut bytes = Vec::new();
         reader.read_to_end(&mut bytes).await?;
         let image_type = match settings.format {
-            ImageFormatSetting::FromExtension => ImageType::Extension(ext),
+            ImageFormatSetting::FromExtension => {
+                // use the file extension for the image type
+                let ext = load_context.path().extension().unwrap().to_str().unwrap();
+                ImageType::Extension(ext)
+            }
             ImageFormatSetting::Format(format) => ImageType::Format(format),
         };
         Ok(Image::from_buffer(