diff kitten: Report errors converting images

kittens/diff/collect.py

@@ -142,7 +142,7 @@ def is_image(path):
 @lru_cache(maxsize=1024)
 def data_for_path(path):
     ans = raw_data_for_path(path)
-    if not is_image(path):
+    if not is_image(path) and not os.path.samefile(path, os.devnull):
         try:
             ans = ans.decode('utf-8')
         except UnicodeDecodeError:

kittens/tui/images.py

@@ -230,11 +230,7 @@ class ImageManager:
             self.handler.cmd.gr_command(cmd)
 
     def convert_image(self, path, available_width, available_height, image_data, scale_up=False):
-        try:
         rgba_path, width, height = convert(path, image_data, available_width, available_height, scale_up, tdir=self.tdir)
-        except ValueError:
-            rgba_path = None
-            width = height = 0
         return rgba_path, width, height
 
     def transmit_image(self, image_data, image_id, rgba_path, width, height):