Gracefully handle requests for file:// URLs which point at a directory.

av98.py

@@ -330,6 +330,10 @@ you'll be able to transparently follow links to Gopherspace!""")
         # Use local file, use cache, or hit the network if resource is not cached
         try:
             if gi.scheme == "file":
+                if not os.path.exists(gi.path):
+                    raise FileNotFoundError
+                elif os.path.isdir(gi.path):
+                    raise IsADirectoryError
                 mime = self._handle_local_file(gi)
                 self.active_raw_file = gi.path
             elif check_cache and self.options["cache"] and self.cache.check(gi.url):
@@ -377,13 +381,13 @@ you'll be able to transparently follow links to Gopherspace!""")
 Slow internet connection?  Use 'set timeout' to be more patient.""")
         elif isinstance(err, FileNotFoundError):
             ui_out.error("ERROR: Local file not found!")
+        elif isinstance(err, IsADirectoryError):
+            ui_out.error("ERROR: Viewing local directories is not supported!")
         else:
             ui_out.error("ERROR: " + str(err))
             ui_out.debug(traceback.format_exc())
 
     def _handle_local_file(self, gi):
-        if not os.path.exists(gi.path):
-            raise FileNotFoundError
         mime, noise = mimetypes.guess_type(gi.path)
         if not mime:
             if gi.path.endswith(".gmi"):    # TODO: be better about this