I'll try and fix the E: error but the one I worry about is this;
W: gpodder source: inconsistent-appstream-metadata-license share/metainfo/org.gpodder.gpodder.appdata.xml (cc0-1.0 != gpl-3+)
If you didn't touch the licensing then this is not an issue, if you did something with AppStream we should try to figure out this inconsistency.