Support models without previews.

comfy/latent_formats.py

 
 class LatentFormat:
+    scale_factor = 1.0
+    latent_rgb_factors = None
+    taesd_decoder_name = None
+
     def process_in(self, latent):
         return latent * self.scale_factor
 

latent_preview.py

@@ -53,6 +53,8 @@ def get_previewer(device, latent_format):
     method = args.preview_method
     if method != LatentPreviewMethod.NoPreviews:
         # TODO previewer methods
+        taesd_decoder_path = None
+        if latent_format.taesd_decoder_name is not None:
             taesd_decoder_path = folder_paths.get_full_path("vae_approx", latent_format.taesd_decoder_name)
 
         if method == LatentPreviewMethod.Auto:
@@ -68,6 +70,7 @@ def get_previewer(device, latent_format):
                 print("Warning: TAESD previews enabled, but could not find models/vae_approx/{}".format(latent_format.taesd_decoder_name))
 
         if previewer is None:
+            if latent_format.latent_rgb_factors is not None:
                 previewer = Latent2RGBPreviewer(latent_format.latent_rgb_factors)
     return previewer