Mute unbuffered_flush IOError exception (#2235)

Related to #1416, it doesn't really fix the real error, but instead mutes the exception message.

Like explained in #1416, this "exception Error" while flushing the client data doesn't harm the client-server connection. However, this exception message continuously spams the logs and makes debugging and error finding really difficult.

src/invidious/helpers/helpers.cr

@@ -700,6 +700,16 @@ def proxy_file(response, env)
   end
 end
 
+class HTTP::Server::Response
+  class Output
+    private def unbuffered_flush
+      @io.flush
+    rescue ex : IO::Error
+      unbuffered_close
+    end
+  end
+end
+
 class HTTP::Client::Response
   def pipe(io)
     HTTP.serialize_body(io, headers, @body, @body_io, @version)