media file: fix exception on empty files.

This may happen if a user uploads from a source that returns an error
HTTP response with no data.

app/logical/danbooru/http.rb

@@ -7,7 +7,6 @@ require "danbooru/http/session"
 
 module Danbooru
   class Http
-    class DownloadError < StandardError; end
     class FileTooLargeError < StandardError; end
 
     DEFAULT_TIMEOUT = 10
@@ -111,7 +110,6 @@ module Danbooru
       end
 
       def download_response(response, file: Tempfile.new("danbooru-download-", binmode: true))
-        raise DownloadError, response if response.status != 200
         raise FileTooLargeError, response if @max_size && response.content_length.to_i > @max_size
 
         size = 0

app/logical/media_file.rb

@@ -43,6 +43,8 @@ class MediaFile
     else
       :bin
     end
+  rescue EOFError
+    :bin
   end
 
   def self.videos_enabled?