Explicitly enabled plugin (mpeg2dec) doesn't throw error when implicitely disabled (gpl)
I have -Dmpeg2dec=enabled in totem's Flatpak manifest when building GStreamer. Unfortunately, the new gpl option seems to disable the codec without throwing an error.
The options passed here: https://github.com/flathub/org.gnome.Totem/blob/8e59c5168530aacbe8cef2b1b1f85c2aacba4745/codecs/gstreamer.json#L19 should result in an error because the mpeg2dec plugin can't be built.
The problem was introduced in d4bdbeaa